black cottonwood vs Western balsam poplar

black cottonwood and Western balsam poplar both are nouns.

Word	Noun	Adjective	Verb	Adverb
black cottonwood	Yes	No	No	No
Western balsam poplar	Yes	No	No	No

As nouns, black cottonwood and Western balsam poplar are synonyms defined as:

black cottonwood and Western balsam poplar: cottonwood of western North America with dark green leaves shining above and rusty or silvery beneath

Other synonyms of black cottonwood include Populus trichocarpa.

black cottonwood (noun)	Western balsam poplar (noun)
cottonwood of western North America with dark green leaves shining above and rusty or silvery beneath	cottonwood of western North America with dark green leaves shining above and rusty or silvery beneath
North American poplar with large rounded scalloped leaves and brownish bark and wood