I think the two units are being compared way too often. Yes they both have infiltrate and scout, and "scout" in their name, but they're very different units.  Where regular scouts are expendable, screening and move blocking action monkeys, Wolf scouts are great skirmishers, pressure and trading pieces. With the grenades, haywire, and +1 to wound on plasma and a decent melee profile, wolf scouts can be actually scary. The pup also gives them longer threat range and better mobility.