completely different body structures, completely different types of fur (length, presence of undercoat, curls in some cases) different kinds of ears (large and small, floppy and not) different tail proportions (some are really long others barely exist) and coloration. hell different prey animals in every fucking aspect the domesticated dog covers the entire fucking spectrum of canine. canis familiaris is a complete fucking cope
and yes, that means there totally is a breed of dog that should be classified as a coyote and in this ted talk i will explain why its the chihuahua.