American black bear vs Ursus americanus

American black bear and Ursus americanus both are nouns.

Word	Noun	Adjective	Verb	Adverb
American black bear	Yes	No	No	No
Ursus americanus	Yes	No	No	No

As nouns, American black bear and Ursus americanus are synonyms defined as:

American black bear and Ursus americanus: brown to black North American bear; smaller and less ferocious than the brown bear

Other synonyms of American black bear include black bear, Euarctos americanus.

American black bear (noun)	Ursus americanus (noun)
brown to black North American bear; smaller and less ferocious than the brown bear	brown to black North American bear; smaller and less ferocious than the brown bear