With two files between the pawns, the defending king cannot stay in touch with both. The attacker advances the pawn the king is not blocking, forcing the defender's bishop to give itself up.
Move the c-pawn one file over to b5 and the same opposite-bishop ending becomes a win. The pawns on b5 and e5 are now three files apart (two files between them), and the black king on d7 can only shadow one.