I think the intent of the OP was that GSP looked huge compared to his physique in previous fights. Personally I don't think he looked any bigger than normal. Any visual difference is probably just due to more or less of a tan.
From the pictures though I'd definitely say GSP is slightly thicker. Certainly GSP's legs, mid-section, biceps and shoulders are bigger/thicker than Condits. Carlos might have the same chest size as GSP. Condit is a little pasty compared to George and isn't as ripped which can play tricks visually too.
Ultimately both guys weighed in at 170 and were probably within a couple of lbs of each other in the octagon.