black bear vs American black bear

black bear and American black bear both are nouns.

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

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

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

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

black bear (noun)	American black bear (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
bear with a black coat living in central and eastern Asia