American bison vs American buffalo

American bison and American buffalo both are nouns.

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

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

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

Other synonyms of American bison include Bison bison, buffalo.

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