I've been getting into speedrunning this game recently and I've been playing it on my Vita (using the PSP version from the playstation store). I own the original/PS2 too but it's more convenient to play on a handheld for me.

Are there any major differences between the Vita version and the base version? I noticed the Vita isn't included in the list of versions.

Thanks for the help!

The version is the same as the classic console version, just digitalised. When you buy ff7 from the psn store, you get the iso of ff7 which is then loaded by an emulator on your device. The PSX Disc category allows only PS1 and PS2 consoles playing from discs, any other way to play the game belongs into the PSX Digital category. PSVita or PSP might not be listed there, but they are legit for a submission in that bracket.

@meesbaker I assume if I play the PSN version on PS3, it would be under PS3, am I correct?

The game doesn't have a separate category for PS3, it falls under PSX Digital as the rules even mention PS3 in that category.