any idea what version it is by the size?

Probably bare bones original version or the download on the PS store is compressed.

Why the game size is so relevant for you?

PS1 and 2 games often use unnecessary uncompressed data

The version matters, the size is used to find what version the game is. I want the US released RE that I played on psone as a kid not the clunky barebones release that is missing stuff.

If you want to play the same game you played as a kid, I'd recommend to play it for PS1 then which probably was the version you played.

I liked this version because you have all extra content available and you can cut the doors animations.

Funny thing is, that PSX version of RE2 actually COULD fit on one disc - there was some sort of mistake or miscalculation regarding audio size. You can find some articles about it, but it was explained with more details in "Itchy, Tasty" book.

Since there was no time for more adjustements, they decided to release it on 2CDs, which of course generated more costs, but also made the impression that sequel is bigger then the first one.

So the file size doesn't mean something was cut. You can even do some googling to see, that size of the original game is around 350-370mb per CD.

The PS3 version is an emulated version of the PS1 version, which came on two discs. One for Leon A/B, one for Claire A/B, both probably 350MB at that time, accounting for the 757MB total (you swap between "discs" using a system menu-based for the PS1 Classics). There would have been a ton of replicated data between discs outside of a handful of unique areas and cutscenes.

you dont understand how file sizes work. if you want to check the features then check the features, file size has nothing to do with it.