What are the different versions of PS1 ROMs?

I downloaded some PS1 Roms from http://www.emuparadise.me/roms-isos-games.php and I have a couple of questions.

What is the difference between v1.0, v1.0, etc? Were there different versions of the original discs?

Some ROMs have multiple files titled (Track 0?).bin. Why are the some many files and which one do I burn to a disc?

One file I have is an .bin.ecm. What is this?

Different versions are usually a rerelease like greatest hits or even a bug fix.

Multiple bin files can be combined and ecm is just another (yet again) compression which you can use unecm to unpack. We have guides for these here:

https://www.epforums.org/showthread.php?57757

Thanks, but why do certain games contain multiple bin files instead of just one? If I want to burn them with ImgBurn, do I just select them all like you said? Also there is no cue file sometime. Do I not need it?

Read the guide it tells you what to do with them and includes the cue files that yes you do need unless a game only has s ingle track then depending on the software can burn directly from a bin/img without a cue or ccd file because there is only one track, still best to use a cue to get the correct mode

it's just different methods of dumping, some that come with a single bin+cue are usually games with no CDDA data so only have one track to start with, some of the older dumps are just done like that anyway even if they are multi track or mixed mode CD's the newer dump are verified via redump though and those are done with the tracks stored separately and keep the original layout perfect, though a bit OTT for me as I always convert them back to a single bin+cue