Jon is more creative, lethal, can fight in the clinch and from a distance and has better situational awareness. GSP is likely more techical with his striking, conservative, but more explosive. I don't think GSP has better wrestling than Jon. GSP has a higher percentage shot and better double leg, probably one of the best. His top game focusses more on control and has a better chance of keeping his foe pinned until victory.
Jon may lose top control if he passes too soon or when he looks to finish, but Jon is more dangerous on top. His GNP and submissions are among the best. A fighter can surive with GSP on top for awhile, Jones will end the fight if he's on top for more than a minute or so. Any opponent will struggle with both fighters. GSP will outstrike you or take you down and ride you out. His approach is simple, but it's perfected and sure to win almost all of the time. It's like no one can stop it. It's like GSP wrote the formula for MMA.
Jon has a base strategy also, but with multiple avenues to victory depending on how he's fought. Get passed his reach, he'll look for TDs or clinch fight. If you box him, he'll kick you. If you grapple him, he'll use knees and elbows from the clinch or go for weird lock ups or submissions. If a fighter just keeps to the outside, he'll kick. Jon is lulling people into a trap. GSP show's the plan, and beats you by the plan because he knows it better than you.
Hard to say who is the better fighter. But, I doubt few would prefer to fight Jon over GSP.