Small Thing I've Noticed

When I play the Queen's Gambit, sacrificing a wing pawn to attack/deflect my opponent's center pawn, they always decline, defending their pawn instead of using it to capture. This makes sense, declining the Queen's Gambit seems to be the generally preferred approach.

But, when I play the Caro-Kann and they avoid my D pawn's attack by advancing their E pawn, I respond by pushing my C pawn to c4. It's almost the exact same position as after I push my C pawn in the Queen's Gambit, only my opponent has an advanced pawn. For some reason, my opponent's are usually far more inclined to capture my wing pawn in the Advanced Caro-Kann than they are in the Queen's Gambit.

Is there a particular reason for this? Does their having a pushed pawn affect the theory in such a way that capturing is better for them here than it is in the Queen's Gambit? Or is it just that they aren't really processing the position in the same way that they are there?