Hares have black markings on their fur.
Hares have very long and strong hind legs, more so than rabbits.
A young hare is called a leveret and a young rabbit is called a kitten, kit, or, least correct but very commonly, a bunny.
Rabbits are altricial i.e. their young are born blind and hairless. In contrast, hares are generally born with hair and are able to see (precocial). Young hares are therefore able to fend for themselves very quickly after birth.