red birch vs Betula nigra

red birch and Betula nigra both are nouns.

Word	Noun	Adjective	Verb	Adverb
red birch	Yes	No	No	No
Betula nigra	Yes	No	No	No

As nouns, red birch and Betula nigra are synonyms defined as:

red birch and Betula nigra: birch of swamps and river bottoms throughout the eastern United States having reddish-brown bark

Other synonyms of red birch include black birch, river birch.

red birch (noun)	Betula nigra (noun)
birch of swamps and river bottoms throughout the eastern United States having reddish-brown bark	birch of swamps and river bottoms throughout the eastern United States having reddish-brown bark