Bunnies are the 'baby's rabbits, rabbits are the adults, and hares are a different mammal, but are basically just large rabbits.

Rabbits and hares are from the same family and are, therefore, related (so there really isn't much difference). A rabbit is an adult, a bunny is a baby or young rabbit, and a hare is fast and larger than a rabbit, The word "bunny" is a just nickname for rabbits and hares -- it means the same thing as "rabbit" or "hare". Maybe I 'm wrong...