In terms of differences between the two, hares are physically larger than rabbits, with longer hind legs, larger feet, and longer ears with black markings, and rather than burrowing into the ground like rabbits, hares build simple nests in the grass. The only rabbit to build its nest above ground is the cottontail rabbit.The nature of their respective nesting sites points to another major difference between rabbits and hares. Newborn hares are born precocial, meaning that they're born fully formed, with their eyes open and covered in hair. This means that baby hares require very little parental care. Rabbits, however, are born altricial, or in other words, helpless. Blind, naked, and unable to fend for themselves, newborn rabbits require a great deal of parental attention, and their vulnerable state is why they nest in more protected dens underground.Rabbits are also more often domesticated; pet rabbits can be very social animals. Hares are usually happiest solo in the wild.