More than you ever wanted to know about rabbits.

First, some key word definitions -- 

precocial: born at a relatively advanced stage of development, requiring only a short period of care by parents. Hooved animals, for example, have precocial young - able to get up and run within minutes of birth

altricial: born at an early stage of development (usually hairless, blind, with limited movement), requiring a long period of care by parents. Humans are altricial, as are cats, dogs, etc. Most predators are altricial, as they require a longer period with the parents to learn hunting behaviors.

And away we go...white rabbit or march hare?

Rabbits and hares are both lagomorphs (the other member of the family is the pika). However, they differ quite radically in terms of both appearance and behavior. Hares tend to have longer ears and bigger feet in proportion to their body size than do rabbits. The reason for this is that hares live in open spaces and escape predators by running like mad, whereas rabbits tend to live in mixed vegetation areas or woodland, and escape predators by running for cover and hiding. Rabbits are communal, living in underground warrens, either dug by themselves or, preferably, found abandoned by another animal, which the rabbits move into and modify. They live in large family groups and give birth underground to altricial young, called kittens, who stay underground in the warren until they are almost weaned. The mother rabbit leaves them underground when she goes out to forage, and returns quite rarely in comparison to other mammals with altricial young - sometimes only a couple of times in 24 hours. This is probably to protect the location of the warren from predators. When the babies grow up, depending on available resources, they either dig their own section of the warren and stay, or strike out on their own, searching for nearby warrens to join.

Hares are solitary creatures who do not dig warrens. They live entirely in the open (although mother hares dig "forms", which are basically shallow depressions in the ground, that the young can hide in for a day or two). The young are precocial, born fully furred and ready to run. They are called leverets. After a day or two in the form, baby hares will scatter, and come back to the form only at dusk, where the mother will meet them to nurse. The nursing period is very short, and when it is over the young disperse themselves as widely as they can. Female hares are capable of conceiving a second set of young before the first set is born, which is called superfetation. The only other animals known to do this are kangaroos.

Rabbits and hares are both highly preyed upon, so they have developed reproductive strategies to keep the species alive. Both rabbits and hares can re-absorb unborn litters if environmental conditions are not positive, and both species will eat their young if they feel threatened (this is to allow them to have a second litter sooner). Both species reach sexual maturity at about three months. Only hares are capable of superfetation, which is probably because, as solitary animals, they have fewer chances to mate. Rabbits are, however, capable of conceiving while still nursing a litter, as the gestation period and the weaning period are about the same length.

Common names for animals often cause confusion - the american jackrabbit, for example, is a hare. In the UK, the European rabbit is often referred to as a hare. There is, in fact, also a European hare, but it does not occur in the UK. The confusion is furthered by the fact that many people are aware of the genus name "lepus" due to horror movies and such, and think it applies to rabbits, but hares are actually lepus - rabbits have several different genuses, depending on geographical origin. (it is the european rabbit that has caused such destruction in areas it has been introduced to, such as Australia. pretty much all rabbits descend from this rabbit.)