mountain birch vs swamp birch

mountain birch and swamp birch both are nouns.

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

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

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

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

mountain birch (noun)	swamp 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