Final answer:
New World monkeys, found in South America, possess broad noses and prehensile tails, whereas Old World monkeys, located in Africa and Asia, have narrow noses and lack prehensile tails, exhibiting sexual dimorphism and diverse habits.
Step-by-step explanation:
The main differences between New World and Old World monkeys are both anatomical and behavioral. New World monkeys, such as tamarins and the pygmy marmoset, are native to South America and are known for their broad noses with outward-facing nostrils, known as platyrrhines. They are arboreal with prehensile tails and tend to form pair bonds. On the other hand, Old World monkeys, found in Africa and Asia, have narrow noses with downward-facing nostrils, known as catarrhines. They include both arboreal and ground-dwelling species, exhibit sexual dimorphism, and do not form monogamous relationships as frequently.
Other characteristics that differentiate them include the socioeconomic relationships within species, dental and skeletal structures, and their distribution around the world due to geographical and environmental variations that affected their evolution.