The difference is, you moron, that Sampras was more vulnerable in the earlier rounds at W because of a variety of reasons, namely fast grass, less seeds, way more serve volleyers in his day, etc etc. But if he could survive the first 5 matches, which meant getting more and more match play under his belt, he would go onto win Wimbledon 100 per cent of the time.
Now compare that to today, where the FO is as good a warm up for W as Queens is, where no one comes to the net anymore, where the top seeds have greater protection against floaters in the draw, and it's plain to see why a player of Federer's ability can cruise through to 9 semifinals/finals. But once there where he was playing players of similar ability, he was far more vulnerable than Sampras was...in the biggest match of the year.
So in conclusion, only because you are a bit stupid:
Earlier rounds:
Sampras more vulnerable because of tougher conditions and tougher grass era. Continuation of FO for Fed.
Final (the biggest match in tennis):
Sampras was super man. Federer was good unless he was playing someone who actually had talent.
End of story.