weight and muscle size have very little correlation, unless you guys are talking about absolute strengtht, in wich case adipose tissue plays a much bigger role than actual muscle.
Powerlifter aren't necessarily big, neither are Olympic weighlifters, yet they are WAY, WAY, WAY stronger than most bodybuilders, especially sin roids.
Bodybuilders are predominantly type IA muscle fibers, those are the fibers that have the greatest hypertrophy potential, but do not contribute significantly to either explosive or absolute strength
Type IIB fibers, the ones displayed on sprinters and Olympicweightlifters, are responsible for strength.