American buffalo vs American bison

American buffalo and American bison both are nouns.

Word	Noun	Adjective	Verb	Adverb
American buffalo	Yes	No	No	No
American bison	Yes	No	No	No

As nouns, American buffalo and American bison are synonyms defined as:

American buffalo and American bison: large shaggy-haired brown bison of North American plains

Other synonyms of American buffalo include Bison bison, buffalo.

American buffalo (noun)	American bison (noun)
large shaggy-haired brown bison of North American plains	large shaggy-haired brown bison of North American plains