Even though only one stage is available in this demo, numerous changes can be found that aren't in later builds nor in the final. Some of these are clearly a work-in-progress (such as the 2-Player Mode), as not much content in this build have been finalized yet.
One of the more obvious differences from the final is the Sonic Adventure 2 logo. It contains most of the same characteristics of the final one, just with less colors and style. The overall title screen is fairly different, but like the logo, it has the same elements, just dark.
While it's barely visible, Sonic's artwork in the background of the title screen is based on an alternate version of his portrait that isn't wearing the SOAP shoes.
A stripped-down version of 2-Player Mode is present in the demo, but can't be activated through normal means and will crash after completing the level due to the other stages not being present.
The demo version of 2-Player lacks certain features, such as a functioning split-screen.
In the final, the player has the option of playing a best of 3 match or a best of 1 match. In the demo, best of 3 is the only mode that exists.
Sonic is missing the light shoes upgrade.
Demo
Final
Sonic Wind has a different name and animation in the demo. In the demo, the attack is called "Long Range Homing" ("Long Homing" in Japanese) and contains a swirl of bright colors in comparison to the rough blue swirl of the final.
Cutscene
(from 2:18 to 3:13)
In the one cutscene of this demo, there are a few changes.
Obviously, Sonic is wearing different shoes. In the final, Sonic starts out wearing regular shoes, but switches midway through.
In the final, music starts playing lightly in the background while the GUN pilot communicates with the radio tower. The music changes to a more exciting song once Sonic busts out of the plane. In the demo, no music plays until Sonic busts out.
The delivery of Sonic's lines is different from the final. His second line is also a little different from the final, but means the same thing. ("I prefer running!")
The Trial
Final
A notable difference of this demo from the final is in this cutscene, at the part where the GUN pilot says, "What?!" in the final. In the demo, this was translated in the subtitles as "What the hell?" Clearly, someone decided that Sonic games shouldn't have curse words. Yet.
UI
English text is written with Impress (the same font it used in the first game). In the final game only the Japanese text uses this font, with English text instead using Comic Sans. Comic Sans is in the demo, but as the demo only has English and Japanese text, it goes unused (It only appears as it did in SA1 - in the slots used for French, German and Spanish).
Demo
Final
Aside from the font difference, the pause menu has a slightly different design, featuring a much lighter border and lacking text to denote which player paused the game.
Character Differences
General
The Ancient Light and Mystic Melody upgrades can't be obtained via picking them up in the levels yet.
Aside from Sonic, none of the characters have a functional life icon, either displaying a placeholder graphic or taking random textures that are currently loaded in Shadow's case.
Sound data for every character besides Sonic is broken in some way. Most sound triggers often result in a cacophony of noise or cause an unrelated sound from a different sound bank to play.
Sonic
Demo
Final
Just as with the cutscene, Sonic doesn't have his Soap shoes yet. He's wearing his regular shoes. This applies to both his 1P Model and his 2P Model.
Demo
Final
The Light Shoes are fully functional, but Sonic only wears them in the gameplay demo. Like his regular shoes, these also have a different design to the final game.
Demo
Final
The Flame Ring's fire somersault has a simpler effect in this version, lacking the fire in front of Sonic. The fire sprites that trail behind Sonic use the generic fire blast particles from the EFFTEX_COMMON texture pack instead of the unique fire sprites found in the final version's S_EFFTEX texture pack. These differences also apply for Shadow.
The Magic Hands have no upgrade model, nor do they have a corresponding Level-Up Item model that can be found in the levels.
Texture Differences
City Escape
A number of textures in this version of City Escape are different to the ones seen in the final game.
Demo
Final
Notes
The largest ad is for Phantasy Star Online in the demo. In the final, it shows Chao in Space 2 instead.
"NINO'S PIZZA" was changed to "PIZZA SONIC2" in the final.
This ad for "The Pixel Noise" was completely removed for the final and replaced with Soap shoes ones.
Different text at the top, saying "COMING ON DVD!!". In the final, it says "COMING TO YOUR HOME" instead.
Brighter.
Brighter.
1-Up Icons
The 1-Up icons were re-rendered in the final game.
Demo
Final
Other Differences
Animations
When Sonic pulls off a "Nice!" trick, he does a front flip as opposed to a regular turn of the board seen in the final. This admittedly looks more fluid than the simple turn of the board on the final.
When Sonic pulls off an "Awesome!" trick, he essentially does a version of the "Cool!" trick that includes more turns. On the final, this became a rotating, high-speed turning trick.
Gameplay
The "Tight!" bonus obtained by homing attacking the GUN Hunter at the foot of the stairs in the enclosure after the boarding section, grinding up the rail between the stairs, and homing attacking a second GUN Hunter is not present.
The two "Nice!" bonuses obtained by grinding down the two rails immediately after the aforementioned "Tight!" bonus is instead a single set of three links spanning both rails that results in a "Cool!" bonus.
The best item the player can get from a checkpoint is a regular shield, not a magnetic one. Because of this, it's possible to get a magnetic shield in the level, and then have it replaced with a regular shield at a checkpoint.
Though unobtainable normally, all of Sonic's upgrades are in the game and can be obtained via hacking. They're all functionally the same as their counterparts in the final game aside from the bounce bracelet, which has very dodgy collision. Using the bounce attack can cause Sonic to clip through objects such as steel containers.