In Super Smash Bros. Ultimate, there are Battlefield and Ω form stages. Some of these look very different from each other at the bottom; compare Halberd and Flat Zone. While they look different, do these stages actually have different collision on the bottom?
Update: As of update 7.0.0, Garreg Mach Monestary is different
For whatever reason, the stage itself is a positioned one unit higher on the screen. So the top blast zone is one unit closer and the bottom blast zone is one unit further.
This is thought to be a bug that will end up patched out, but until then, the stage's Battlefield/Omega forms are banned in tournaments.
You can see more on this tweet: https://twitter.com/Lyra_GP/status/1223989295830179842
Below you'll find the old answer:
No, all Battlefield/Omega stages have exactly the same bounding boxes and dimensions.
From the Wiki Page:
In the introduction of Ω form and Battlefield form stages in the E3 2018 Nintendo Direct, Masahiro Sakurai stated that all Battlefield forms will be identical, differing only in music and aesthetics.
(note that all Battlefield/Omega stages will be 50% larger when played with 5+ players as in Smash 4)
However, there is one difference that affects gameplay
Smash is actually a 3D game, meaning the hitboxes and hurtboxes of moves and characters all have a Z-axis attached to them. This causes some weird interactions, like this one:
But some stages, like Flat Zone, are "2D" and have no Z-axis. To represent this in the game, the stage has a "flattening effect" on all hitboxes and hurtboxes that pulls them all into the same point on the Z-axis. This 2D property persists when you choose the Battlefield/Omega version of a stage.
For a list of stages with this property, see this reddit thread: All Stages with the 2D Effect