When Mario does a sharp turn, instead of suddenly facing that direction, he will instead turn around to face said direction just like in Shoshinkai 1995.
The stardust uses a different graphic than in the final game, this early graphic is the same one used in the Space World '95 demo, seen here. It was also found in the Gigaleak.
The textbox animation is slower than the final build which; again, is similar to Space World '95 demo, seen here and here.
The Bob-omb Battlefield painting is quite different, having Lethal Lava Land's frame, a larger center Bob-omb with lower feet, different smoke effects, and visible wind-up keys, which were removed from both the final game's painting and Bob-omb models. A later build depicts the final version of the painting.
3rd Floor
Pre E3 1996
Final
The glass covering the pendulum is blue instead of yellow.
The bricks use a different texture.
The Toad that grants Mario a star is absent.
Pre E3 1996
Final
(Source: 30 minutes of E3 1996)
The hallway leading to Dire, Dire Docks wasn't just a straight hallway, but instead took a turn to the right. The room also uses the different brick texture seen in other pre-release screenshots from this time.
Wario was never supposed to make an appearance, and this was just a gimmick they had going on in the booth. No screenshot without him exists, unfortunately.
The blue starting platform's shading is different.
There is a coin ring around the cannon.
The Bob-omb Buddy is placed differently, it's farther away from the cannon base.
There are no trees in this beginning area.
The breakable boxes are placed differently, on the left side of the dirt path. Also there are 3 big boxes, instead of 2 big ones and a small grabbable one.
Signs are nearly absent in this part, except for the one right beside the dirt path.
Different skybox and more primitive UI, but otherwise close to the final game.
Whomp's Fortress
Pre E3 1996
Final
(Source: Nintendo of America E3 1996 "Take Away Video")
There are no Butterflies found in the course, and the sign next to the sleeping Piranha Plant in the beginning of the course is missing. The Piranha Plant also uses a different sound clip for its bites.
Two signs, a Power Star location, and a small cork box are missing from their spots next to the farthest flower bed.
Pre E3 1996
Final
(Source: Nintendo of America E3 1996 "Take Away Video")
Thwomps still use their Space World '95 textures, but they now use square shadows, like the final game, instead of circular shadows like the Space World '95 demo.
There are no floating islands in the level, except for the island made of bricks, which has a star on it.
The Boos possess Yellow Coins instead of Blue Coins, and one Boo can be seen right after the falling floor section. It also has an early face texture.
The railing now uses the final game's design.
Pre E3 1996
Final
This section lacks the Killer Books that emerge from both bookshelves.
(Source: Nintendo 64 Pre-Launch Promotional Tape)
Pre E3 1996
Final
Instead of having a Blue Shy Boo Painting, the attic is shown to only have the Yellow Scaring Boo Painting. It also covers the entire wall instead of only half of it.
The early coin design is seen on the Blue Coin Switch.
A red coin on the right bookshelf is missing, with a yellow coin in its place, suggesting that their placements differed in this build.
Bookends don't give a blue coin when defeated.
Two chairs are on the right side of the table, in the final version, one of these chairs was moved to the other side of the table and both were rotated to face it.
The wall behind the table is pushed further back
The blue Boo painting is missing, leaving a gap between the rooms.
The Vanish Cap box is absent.
In the hallway, there were two small Boo paintings with a containing a single Boo each, inside instead of two per painting.
Boos can be defeated with a jump instead of a Ground Pound.
This is the first appearance of the final's Boo design.
To do: Get an audio clip and pictures.
Big Boo makes a different sound when he gets hit. This would've also applied to other Boos as well.
The Purple Switch in front of the Flamethrower is absent, with a Red Coin in its place, suggesting that the challenge with the timed blocks didn't exist yet.
(Source: NEW N64 Japanese Promo Video/Rare Beta Footage (1995-96) Space World '95 (3:49))
The second Red Coin from the beginning is, instead, located on this spinning platform.
The boss entrance cutscene zooms uncomfortably close to Bowser's schnozz. It's pulled back both in a later revision, and in the final game.
Pre E3 1996
Final
Pre E3 1996
Final
(Source: 関西偉人館/任天堂社長 山内溥, SM64 Research Discord Server)
Bowser's pre-fight dialog is formatted differently. The characters are the same, but the spacing is different.
Pre E3 1996
Final
(Source: Kelloggs Sweepstakes - Nintendo Power Previews 16 segment)
Bowser would drop coins when defeated, much like in Space World '95.
Hazy Maze Cave
Pre E3 1996
Final
(Source: Nintendo N64 B-Roll E3 1996)
The map showing your location is missing, though it's unclear if other maps in the level were missing as well. In the later build, the map was implemented as shown here.
The Metal Cap box is in a different position; it's in the middle of the starting room, instead of right beside Mario's spawn point.
There is a Swooper at the beginning of the left path that was removed in the final game.
Pre E3 1996
Final
(Source: Nintendo of America E3 1996 "Take Away Video")
A jumping Scuttlebug and another Swooper can be seen at the end of the left path, and the sign teaching you how to Long Jump is closer to the bottomless pit.
The Scuttlebug past the boulder area is missing, as seen in the middle screen.
Lifts share the lantern texture, likely as a placeholder.
Scuttlebug
Pre E3 1996
Later pre-release
Final
(Source: Nintendo N64 B-Roll E3 1996, Gamefan Volume 4 Issue 08 August 1996 - Page 12)
Scuttlebugs have an early model that can be found in the leaked source code and, as seen in the GIF above, don't jump and run towards Mario upon eye contact. Instead, they just turn around and walk at normal speed towards him, and don't drop any coins when defeated. A late pre-release version of the enemy had white legs and a lack of fangs.
The Dire, Dire Docks theme uses a different lead instrument sample. This instrument still exists in the final game, known in the decompilation as 42_vibraphone.aiff. There is also an extra part that isn't present in the final.
Tall, Tall Mountain
Starting at 0:32, the Red Coins above the mushrooms are missing. This could be because this build doesn't feature Red Coins yet.
An unknown object, likely a sign, appears in the distance as Mario runs through the mountain's path.
The Fly Guy in the rolling log bridge section is missing.
There's a missing Ukiki in the same section.
The waterfall seems to be silent, indicating that the object the ambient audio originates from isn't implemented yet.
The Crazy Crate seen below the rolling log bridge section is missing, seen at 0:48.
The platforms holding the rolling log bridge in place are different; they are flat instead of sloped. Mario could've walked on top of the surfaces, causing issues with the bridge, and necessitating the change for the final game.
The platform right after the bridge is different too, it has a square shape compared to the final which is more triangular.
This screenshot from the same press kit shows that the star inside the monkey cage works like Klepto's. All stars are collected in these screenshots (which is why in the previous screenshot the star above the lonely mushroom is barely visible), but the star is still yellow inside the cage.
The coin line on the bridge beside the monkey cage is missing, because it is impossible to stand on that location without collecting at least 1 coin.
The wooden texture seen throughout the level is also different. The block in the middle of the texture has a different bevel with yellow hue, that same block is also affected by a dark gradient.
The screw holding one of the moving blocks is flipped horizontally; it's unknown if any other screws in this course are also flipped.