The intro scene is stripped down to one screen: the one in which the Belmont ancestors size up the castle. Though, the visual's rendering is very different from the finalized version's. Its color-scheme is instead a simple tetradic mix of red and blue, and the characters and the environments are uniquely rendered. The heroes, in particular, are unidentifiable; the pair is portrayed as a generic warrior and wizard, whereas in the final version they're clearly Trevor Belmont and Sypha Belnades.

The title screen has no background graphics, and it features a different title-screen theme--one that's exclusive to this demo.
There's no game-starting intro sequences. Rather, after selecting "Start" in the title screen, we immediately jump into action.
Also, there are no between-stage transition screens. Once a stage is completed, and the score his been tallied, the game immediately sends you to the next stage.

The password screen features a rudimentary design. There is no background visual.

If you enter the Konami code (up, up, down, down, left, right, left, right, B then A) on the title screen, you'll unlock a level-select option. It appears on the title screen's top portion. You can manipulate the number by pressing the A, B and C buttons. A increases the number by one, B increases it by ten, and C decreases it by one. Only selections 0-24 load stage sections; if you select anything beyond, the game will crash after the character-select screen fades out.
The options screen offers Easy and Normal difficulties, though there doesn't seem to be any difference between the two modes.
Observing the options screen, we see that "Easy" is the default mode, and the starting life-total is 4 rather than 3. The "Press Start to Exit" text is missing. The SE value stops at 98, whereas it goes up to 206 in the finalized version. The BGM value stops at 19, whereas it goes up to 30 in the finalized version. The Stage 4 and 5 tracks (which aren't heard during the demo) have different instrumentation. The chilling-sounding BGM9 track is exclusive to the demo and particularly to this options screen. And, oddly, the stage-clear track is missing from the BGM selection.
You can further manipulate the beta by inputting commands on the second controller. There are three things you can do: (1) Stage warp to the proceeding or the previous stage by holding up or down on the d-pad and pressing the A button, respectively (note that if you attempt to warp to a previous stage while on 1-1 or warp to a proceeding stage while on 2-6, you'll arrive on a glitched, platform-less version of 2-5 and immediately fall to your death; you'll then restart on 2-5). (2) Replenish all of your health and max out your gem-total by pressing the B button. And (3) toggle off the music and sound effects by pressing the C button (they won't toggle back on until you enter a new section or die).
This build is rough around the edges. There are minor graphical glitches (discolored objects and some sprite-flicker). The action moves slower and with a slight jitter. Character movement is a bit stiff. There are collision-detection issues: platform edges aren't always solid, and sloped surfaces sometimes feel bumpy; the heroes' stair-climbing is most affected by this, the action's animation observed to be very choppy. The hero characters fall forward a bit when they drop from a platform, and at the same time they become unresponsive. And the frame-rate dips significantly when more than six characters are onscreen and when multiple death animations are occurring at the same time; when this happens, the music, too, slows down.
There are some noticeable palette differences.
The sound effects are somehow more primitive- and squeakier-sounding.

        

The character-select boxes feature more-basic background graphics--more-simplified brick patterns.
The "Stage Start" and "Pause" title cards are missing.
Sub-weapons aren't centered in the UI's sub-weapon box.
You can't jump off of stairs. Also, you don't walk down stairs automatically and have to instead hold downward when approaching a staircase.

        

Strangely, if the first candelabra you strike is one of the sub-item-holding variety, it'll drop a coat-of-arms power-up rather than a sub-weapon.
The heroes take less damage.
If you whip or spear-strike during a jump's descent, you'll experience landing lag. In the final version, contrastingly, the heroes' movement remains fluid regardless of the point in which they strike.
If you refrain from inputting commands after John or Eric lands on stairs, they'll be viewed in an exclusive idle pose; the poses appear to be variants of their normal turning sprites.
When the hero takes a hit, the damage doesn't register on his health meter until he lands. In the finalized version, the energy reduction is instant.
The first few frames of John's whip animation have smaller hitboxes, which prevents him from doing what was possible in the finalized version: whipping candelabras or other objects that are just overhead.
Eric's spear-twirl move isn't yet implemented. When you press left or right when holding down the attack button, he instead executes a more simplistic spear-swing move.
Eric rests the spear on his shoulder as he walks, whereas in the final version he carries it at his side.
The handle of Eric's spear has no active hitbox. If the handle, alone, makes contact with an enemy or candelabra, it won't register a strike.
Eric's super-jump move carries him forward a bit after it hits its apex, and it has a one-second rev-up. The move has no attached sound effect.
Both heroes hold their extension attacks (executed by holding down the attack button after it's pressed) for an extra second. When Eric does this with the trident, it results in the weapon's disjoining animation becoming more pronounced.
The sprite for Eric's character-specific special sub-weapon is different.
You can't jump up through a platform if it's just overhead, at a four-tile-high height.
There are only two stages available (the Ruins of Castlevania and the Atlantis Shrine). When the second stage is cleared, you're looped back to the first stage.
For some reason, the UI tracks your time.
Certain musical themes have slightly different instrumentation.
When you defeat a boss, the boss music fades out, whereas in the final version, the boss music instantly stops.
The action freezes the moment you make contact with the stage-clear crystal.

When John dies, he doesn't fade away as he does in the finalized version. Rather, he falls to the ground, turns into a skeleton, bounces back, and then breaks into bony pieces.
After dying, you restart with half your gem-total plus one, whereas in the finalized version you lose all of your collected gems.
There's no death ditty.
Obtained gems and sub-weapons ascend up to the UI and settle into the corresponding locations, and the animation of such is accompanied by a unique sound effect.
If you collect a gem when your gem-total is at 99, you'll earn an extra life. This only happens the first time you collect a gem while the total is at 99.
The UI's blue gem flashes when you have enough of them to use the currently owned sub-weapon.
When you pick up a third coat-of-arms symbol, you receive only a whip/lance upgrade. The character-specific special sub-weapon can only be procured by alternate means (for how to do it, please refer to the second bullet point after this one).
You can't execute an item-crash by simultaneously pressing up on the d-pad and the sub-weapon button. Rather, you can only execute an item-crash under the following condition.

The demo features an unimplemented power-up system. When you procure a sub-weapon that's already in your possession, you power up that weapon to a second level. The sub-weapon's UI display changes form and color--to a deadlier-looking, fiery blue version of it--signifying that it's been powered up. From then on, a simple press of the sub-weapon button will unleash the weapon's item-crash attack. By picking up the same weapon a third time, you'll earn the character-specific special sub-weapon (the Crystal for John and the Spear Head for Eric), which functions as expected.
The spear head earned via the power-up system won't be lost when Eric takes damage.
Eric's spear doesn't become enflamed when he's in possession of a spear head.
The earning of 20,000 points leads to the replenishment of your health.
There's no sound effect to accompany a pot roast's replenishing of your health.
Item-placement differs. In some cases, there are additional candelabras present.
Sub-weapon candelabras can drop whip power-ups.
Coat-of-arms power-ups drop from candelabras when your gem-total reaches 40, whereas in the final version, you need to reach 30.
Enemy-placement differs. Some enemies are shuffled around. And certain enemies have different HP-totals.
Enemies can drop screen-clearing mirrors.
You can take damage from minor enemies and bosses' death animations.
You can despawn enemies by scrolling them off the screen.
If it also serves as accompaniment in a following stage section, a stage's musical theme will restart after you transition over to it.

The demo contains an exclusive item: a skull-adorned book whose procurement produces a random effect. It will do any of the following: cause the music to switch to one of the three classic tracks (Beginning, Bloody Tears or Vampire Killer), any of which will continue playing for the duration of the stage or until you die); fully replenish your health; render you invincible; provide you five gems; or even punish you with one level of whip regression! It was probably intended to be a "Wild Card"-type item.
Continues are unlimited.

There's a 1up candelabra hidden atop the screen, amongst the treetops, in the stage's opening area.
There's no invisibility crystal in the first hallway.

A peeping eye is placed on the final screen of the first hallway.
A skeleton, rather than a peeping eye, occupies the first screen of the between-hall connector area.
In the between-halls connector area, the aforementioned "strangely adorned book" is hidden in the breakable wall in place of a pot roast (the screenshot depicting this can be seen above, the "General Differences" section).

        

The fish men and the hellhound boss sport different sprite designs.
The water in the fishman section is missing its surface foam and the resulting rushing animation.

The last candelabra in the fishman section holds a 1up. By leaving and reentering this section, you can collect it again and again.
The Hellhound battle differs in that fewer windows shatter when the beast howls and all of its attacks can be canceled out--the animations completely preempted--by whip/spear strikes. Thus the Hellhound can easily be backed into a corner and pummeled without interruption. When its death animation has completed, you simply move on; you don't have to first finish it off by administering a finishing blow.

1-6's skeletons are of a blue-colored variety. There are only three of them compared to six in the finalized version. Also, the room's bat is placed more to the right.

1-7's spiked gears sport a red hue. Also, this section is missing its third background layer--the visual of a castle wall; in its place is only blackness.

1-8 is also missing its third background layer--the blue brickwork; in its place is only blackness.
Mace skeletons die in one hit. Also, their attack animation lasts longer due to an added swinging cycle.
The 1up candelabra is missing from the penultimate stage area wherein you ascend by traversing up a dragon's spine.

The final section's--the castle keep's--background imagery is different. The sky is cyan-colored, and the full moon is completely lacking for detail; it's merely a light-blue circle (likely a placeholder).
John can kill the castle keep skeledragon in two hits whereas in the finalized version it takes three hits to do it.
The Mecha Knight is less active and can be beaten more easily. It's possible to crowd it, too, into a corner and pummel it with interruption.

There are no bone pillars present in this stage.
The helmeted golem knights are more defensive and can't be destroyed with body blows; rather, you have to strike their exposed legs.

In 2-2, the flood section, golem knights replace minotaurs. Also, there are no platform-circling balls of destruction in this section.
2-2 and 2-4's water has no surface foam and instead series of glitchily animated rectangular objects.

At about 2-2's halfway point, there's a candelabra containing another one of those "strangely adorned magic books." It's found on the left side, overhanging a gap.
2-2's 1up candelabra is missing.

The Water Magician fight has no boss-music accompaniment and doesn't utilize the Enemy meter. Also, the Water Magician dies in only three hits.
You can bypass the Water Magician fight altogether by simply continuing to head right and exiting via the stairway. All the while, though, he'll continue to make the water rise.
The Armor Lord and Red Armor Lord bosses don't appear.
You enter Stage 4-2 via stairway, whereas in the final version, you simply drop into it.
The platforms you stand upon in 2-4 have a different look: They're green barnacled blocks. Unlike the rafts that replace them in the final version, these blocks don't sink when you stand on them.

Medusa Heads sport a different sprite design, and they have a unique property: When they get close to you, they stick out their tongues.

        

If you fall too far beneath the water in Stage 2-4, you'll die instantly (whereas in the final version, you continue to take damage until the water lowers to head-level).
Section 2-5 contains harpies (of the regular and spear-carrying varieties) and more minotaurs in general. Also, minotaurs replace bone pillars and the lone skeledragon that's strangely missing. All such minotaurs attack with weapons, including parts of broken pillars, which they're not supposed to wield until Stage 3--the one that actually contains the white pillars that they rip apart; they have no charge attack.
2-5 has some structural differences: some platforms differ in height, including the final of those you have to clear away with a weapon-strike.
2-5's breakable wall can't be fully destroyed. This appears to be a result of its containing pillar being too short in height, the contraction robbing the breakable wall of a necessary fourth destructible tile.
The finalized version's penultimate screen, which contains those three charging Minotaurs, is missing; instead, the final horizontal area empties right into the Golem's boss room.

The Golem room's textures (both foreground and background) feature unique color-schemes: light greens and blues compared to the final version's dark yellows and reds.
As you lower into the Golem's chamber, there's a brief period (about three of four seconds) in which you're unable to attack it with sub-weapons. The throwing animation will play, yes, but no sub-weapon will be released.
At no point does the rocky exterior portion of the Golem's head shatter. It remains as is for the entire fight.
As mentioned: You can take damage from the Golem during its death animation. If you allow yourself to be pulled into the animation's center, you'll suffer multiple hits before you escape.