The two primary groups of monkeys are distinguished by their range. The New World monkeys live in Central and South America while the Old World monkeys live in Africa, India and Southeast Asia. But their range is not their only differences. There are a variety of other traits that distinguish Old World and New World monkeys. Their nose and their tail are two examples. Old World monkeys have a long rostrum and nostrils that are positioned close together and have a downward facing nose. New World monkeys have a shorter rostrom and their nostrils are positioned far apart, on the sides of their nose. As for the tail, Old World monkeys do not have a prehensile tail; New World monkeys do.