per above. there are differing standards per rom info or dumping group, per console, and even per website. some examples:
-you may see "REV 00" and the like for mega drive games. there's also stuff like sonic 1's "REV XB", referring to the sonic mega collection which had been developed for xbox apparently.
-you may see "PRG0" for nes games. this raises the question of what exactly smb's "PRG1" is, as there's only one JU rom in most newer dumps.
-you will generally see "V1.0" for snes games, and for certain dumps of game boy games. no-intro uses the "Rev B" system for game boy, though. and i think it's actually "<no label>" for the earliest version, then "Rev A", then "Rev B", which would make sense.
with the game boy bit in mind, these all mean about the same thing: "REV 01" = "PRG1" = "V1.1" = "Rev A". i assume some of the differing standards come from something in the hardware.
by the way, if you see any snes games labeled "(NP)", those are related. these roms were released through the japanese "nintendo power" service (completely unrelated to the north american magazine of the same name) and generally have some bugfixes; you will often find a "V1.1" or even ".2" attached to them, unless the game is NP only.