1990= No emblem on hood, "INTEGRA" sticker on rear with trim level on right side above tail light
1991= Acura emblem on hood, Acura emblem in center of rear, "INTEGRA" emblem on right corner and "ACURA emblem on left corner.
both 90-91 were OBD-0 (130HP), had the same everything else.
1992-1993= Bumper looks happier (different bumper support to), Rear bumper got a little bit of a flare at the bottom (hatchback only), tail lights got the amber treatment and went to OBD-1 (140HP).