Unless Canada is different than US (seems like they got the 140 chassis in 91, rather than 92), a 91 300SE is a completely different car than a 92 300SE. Other than the fact that they're both made by Mercedes, they share practically nothing in common.

91 has the M103 motor, and a 4-speed auto.
92 has the M104 motor, and a 5-speed auto, and LOTS more gizmos.