caro-kann vs Slav

The Caro-Kann developed before the Slav, so no.
Having a White pawn at c4 or at e4 makes quite a difference :
*1. e4 c6 2. d4 d5 3. e5 is a very important option while 1. d4 d5 2. c4 c6 3. c5 makes no sense.
*Exchanging on d5 creates an asymmetrical pawn structure in the Caro-Kann, whereas the Exchange Slav keeps the symmetry.