Ape vs Monkey

Apes and monkeys are both primates, but they are different groups. Monkeys number nearly 200 species and nearly all have tails. Apes, including the great apes and smaller ones like siamangs, have no tail at all, which makes the tail the first thing to check at a zoo or in a photo.

The great apes are bonobos, chimpanzees, gorillas, orangutans and humans. Names add confusion, since orangutans, nicknamed red apes, are sometimes mistaken for monkeys. Apes also tend to be larger and slower to raise young, so build and tail together are the safest check. Apes also tend to be larger and slower to raise young, and they usually show a broad chest and long arms.

Ape vs Monkey side by side

Last verified October 2026. Typical values; individual animals, products and local prices vary.

When you are looking at which

Ape

• A primate with no tail at all, however large or small it is.
• A big animal with long arms, such as a gorilla, chimpanzee or orangutan.
• A broad-chested body that sits upright or knuckle-walks rather than running on all fours.
• A siamang, the small ape that swings by its arms, which counts as an ape despite its size.

Monkey

• A visible tail, whether long, short or just a small stub.
• A slim, narrow-chested primate, which is the skeleton type Britannica notes for monkeys.
• A baboon, macaque, capuchin or howler seen in a zoo or in the wild.
• A smaller primate with a narrow chest rather than the broad chest of an ape.

How this works

The quiz uses five traits a visitor can see at a zoo or in a photo: tail, size, build, movement and named species. Each answer points to ape or monkey, and the more cues agree, the stronger the result. Each answer points to ape or monkey, and when all five agree the result is reliable. Mixed answers are shown as a tie.

The tail rule is very reliable but not perfect in everyday language, since common names are inconsistent. Use the species name when you can. Treat unusual cases, such as a tailless animal with a short body, as a reason to look up the species name before deciding.

Where these numbers come from

The figures and defaults on this page are based on:

• Auckland Zoo: Apes vs Monkeys, Tail rule and longer parental investment in apes (checked October 2026)
• Smithsonian National Zoo: Are Orangutans Monkeys?, Ape size, build, no tail, and list of great apes (checked October 2026)
• Britannica: Monkey, Nearly 200 monkey species, tail rule and narrow chest (checked October 2026)
• San Diego Zoo: Chimpanzee, Chimps are tailless apes that knuckle-walk (checked October 2026)

Educational guide. Primate classification is revised often, so check a current zoo or museum reference for a specific species.