Remember both of them can use the bow. It just hurts more when you are a ranger. Melee hurts more when you are BM.
Beastmaster's get more HP, somewhat less armor (they both suck in armor), wolves (which can make or break your victory in PVP), and 10hp damage Axe of Doom (equal to the Samurai's Crystal Katana, and second only to the Ninja's crystal katana, for highest raw melee damage in all of heroes).