Western paper birch vs Western birch

Western paper birch and Western birch both are nouns.

Word	Noun	Adjective	Verb	Adverb
Western paper birch	Yes	No	No	No
Western birch	Yes	No	No	No

As nouns, Western paper birch and Western birch are synonyms defined as:

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

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

Western paper birch (noun)	Western 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