swamp birch vs mountain birch

swamp birch and mountain birch both are nouns.

Word	Noun	Adjective	Verb	Adverb
swamp birch	Yes	No	No	No
mountain birch	Yes	No	No	No

As nouns, swamp birch and mountain birch are synonyms defined as:

swamp birch and mountain birch: birch of western United States resembling the paper birch but having brownish bark

Other synonyms of swamp birch include Betula fontinalis, water birch, Western birch, Western paper birch.

swamp birch (noun)	mountain birch (noun)
birch of western United States resembling the paper birch but having brownish bark	birch of western United States resembling the paper birch but having brownish bark