buffalo vs American buffalo

buffalo and American buffalo both are nouns.

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

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

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

Other synonyms of buffalo include American bison, Bison bison.

buffalo (noun)	American buffalo (noun)
any of several Old World animals resembling oxen including, e.g., water buffalo, Cape buffalo	large shaggy-haired brown bison of North American plains
large shaggy-haired brown bison of North American plains
meat from an American bison

buffalo (verb)	American buffalo (verb)
intimidate or overawe