What is the difference between bison and buffalo?

Bison and buffalo are part of the same family, the Bovidae, and although they are often used interchangeably, here are some of the main differences:

Horns: Bison horns look like cow horns, while buffalo horns are larger and have a more pronounced arc. The African buffalo, most notably the water buffalo, has horns that start on top of its head and extend to the sides, creating a guard of a sort that is useful when fending off attackers or staking out territorial claims. The bison do not have this feature.

Hump: Bison have a larger hump on their shoulders than buffalo, used to plow through snow or other cold-weather obstacles found in North America and Europe.

Homeland: Buffalo have never lived in North America, so the ones you find in the American West and Great Plains are bison. Buffalo are native to Africa and South Asia. Early explorers in the US saw millions of bison and, because they resembled the buffalo of Africa and South Africa, mislabeled them.
https://www.livescience.com/32115-bison-vs-buffalo-whats-the-difference.html