CU Has It Wrong

The Buffalo that Americans refer to is actually a Bison. It is also called the American Buffalo.

Only partly wrong I suppose. For corroboration,

To many people, 'buffalo' is the popular name often used to describe North American bison; however, this is a misnomer. In fact, buffalo are distinctly different animals from bison. Although both bison and buffalo belong to the same family, Bovidae, true 'buffalo' are native only to Africa and Asia.