What do monkeys have that apes do not?

The easiest way to distinguish between a monkey and an ape is to see if it has a tail. Almost all monkeys have tails, while apes do not. Also take note of the primate’s body shape, size, and other physical attributes. Apes are generally larger with wider chests and almost naked faces. Monkeys are smaller with more narrow chests and they have hair on their face.

Source: PASA