Gracie was on a whole other level in his era as well. We tend to forget the ones who brought the sport to where it is. Just a comparison. Gracie was killin cats before they had weight classes if we remember. He was smokin people that outweighed him by 100-150lbs.
Gracie was the only person who knew BJJ.
Standup guys were usless against him. As soon as the fight hit the mat it was over.
Wrestlers could only ground and pound, but with his BJJ Royce was able to defend on the ground and work for subs.
Gracie was strictly a BJJ blackbelt coming in and fighting guys who have never seen BJJ before.
GSP on the other hand is the best MMA wrestler in the UFC, one of the best stand up guys, and has a BJJ game that is high level and he has hardly had to use it.