This is a very good question and you probably won't find an answer. Best way would be to look at the code and spot the differences. For some games they might have just changed the revision code for the hell of it when sending it out back in the day.
On some games they usually fixed glitches or tweaked movesets/engine. Like X-men vs Street Fighter. There are three US revisions, each one removing different infinites. The last revision is the one that got ported to the Saturn and iirc allows you to select more than 2 colors. X-men Children of the Atom has differences in attract modes on version 1-3 along with cutscene differences. Also different infinites but most people have/will play version 3.0.
Vampire hunter also has two revisions
Version Differences
1995/03/02: Initial Japan version (Japan tourney and DCC viable version, also used in Darkstalkers Resurrection)
1995/03/16: Final Japan Revision (All other versions including later World reigon verisons are based on this version)
Bugs and Glitches
1995/03/02 only:
Bishamon's ES Kirisute Gomen doesn't use up any meter
Gallon's ES wild circular will use up all levels of meter
Felicia's ES hell cat will use up all levels of meter
Aulbath's ES Crystal Lanser will use up all levels of meter
Aulbath's ES Sky Neptune will use up all levels of meter
Pyron's ES Planet Burning will use up all levels of meter
Phobos/Huizil jumping MP knocks down grounded opponents.
Even Super Street fighter II grand master challenge X, Street fighter Alpha 3, Vampire Savior, and even beat em ups have different revisions in the same region. Not much has been documented on these either due to there being no difference, rare bug fixes, or no one gives a shit. I would lean towards no one gives a shit and no significant difference (even coming from a competitive standpoint).