The 8372A and 8375A support 1MB chipmem, whereas the 8372B and 8375B support 2MB chipmem, those are the differences.
OCS A2000s & A500s had 8370 (NTSC) or 8371 (PAL). I once had an old A2000 rev 4 (often called rev 3.9 or model A) with an 8367 Agnus, IIRC. It was a PAL A2000. Maybe that's the one PAL A1000s also used, I don't know.
