I don't think there is a difference but I may be wrong. These are the HP figures for each year but I am honestly not sure if the change in HP also changed the 5 speed.
Edit: they are diff.
Transmission: 90-91: A1,S1, cable
Transmission: 92-93: YS1, cable
I have no idea what the diff is though. like I said it could be final drive.
Gen II Tegs
RS, LS, GS B18A
Horsepower: 130@6000 RPM
Torque: 121@5000RPM
Redline 6500 RPM
RS, LS, GS B18B 92-93
Horsepower (hp), 140 @ 6300 RPM
Torque (lbs-ft), 126 @ 5000 RPM
Redline 6500 RPM
GSR
Horsepower: 160@7600
Torque: 117 @ 7000
Redline 8000 RPM