genus Betula vs American white birch

genus Betula and American white birch both are nouns.

Word	Noun	Adjective	Verb	Adverb
genus Betula	Yes	No	No	No
American white birch	Yes	No	No	No

genus Betula (noun)	American white birch (noun)
a genus of trees of the family Betulaceae (such as birches)	small American birch with peeling white bark often worked into e.g. baskets or toy canoes