bison vs Bison bonasus

bison and Bison bonasus both are nouns.

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

As nouns, Bison bonasus is a hyponym of bison; that is, Bison bonasus is a word with a more specific, narrower meaning than bison:

bison: any of several large humped bovids having shaggy manes and large heads and short horns
Bison bonasus: European bison having a smaller and higher head than the North American bison

Other hyponyms of bison include American bison, American buffalo, Bison bison, buffalo, aurochs, wisent.

bison (noun)	Bison bonasus (noun)
any of several large humped bovids having shaggy manes and large heads and short horns	European bison having a smaller and higher head than the North American bison