Bison bison vs American bison

Bison bison and American bison both are nouns.

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

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

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

Other synonyms of Bison bison include American buffalo, buffalo.

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