Rabbits are not rodents, but are part of the Lagomorpha order of animals. They were, however, classed as Rodentia until around 1912, when the Lagomorpha order was recognized. It is thought that rodents and lagomorphs share a common lineage, and so both are grouped together under the superorder of Glires
Rabbits have two sets of incisors, one behind the other, and this is the major difference between them and rodents. Rabbits live in groups and usually live in burrows underground, called warrens, and half of all the rabbit's population reside in North America. Most of South America has a single species, the tapeti, which spread to the continent during the Great American Interchange.
Rodents, however, are native to all continents except Antarctica. Out of the 4,000 living mammal species on the planet, 1,500 of those are rodents, making it the largest group of mammals. Mice, rats, hamsters, porcupines, woodchucks, squirrels, chinchillas and beavers are all included in the rodent order.
Other mammals found in the Lagomorpha order are hares and pikas. All are small to medium-sized herbivores, and they have two types of droppings: the common, solid spherical droppings and a soft grease-like pellet. The latter is re-consumed by the mammal as it contains many nutrients and vitamins and allows them to utilize maximum nutrition from the food they eat.