Ok, we're way off topic, but without going to deeply into a scientific explanation of the differences, primates are divided into three categories, hominoids (better known as apes), monkeys (subcategorized into old world and new world monkeys), and prosimians (which include lemurs among other things.)
Apes are divided into two categories, great apes and lesser apes. The four species of great apes are orangutans, gorillas, chimps, and bonobos (also known as pygmy chimps.) There are 16 species of lesser apes, which most of us know as gibbons. These are the species with the distinctive broad shoulders and long arms that you see swinging hand over hand through trees for sustained periods of time. That mode of transport is called brachiating, and it is unique to gibbons. A monkey may swing from its hand occassionally, but they mostly move throught the trees by running along the branches.
End of science class. sorry for being off topic.