black cottonwood vs swamp cottonwood

black cottonwood and swamp cottonwood both are nouns.

Word	Noun	Adjective	Verb	Adverb
black cottonwood	Yes	No	No	No
swamp cottonwood	Yes	No	No	No

As nouns, black cottonwood and swamp cottonwood are synonyms defined as:

black cottonwood and swamp cottonwood: North American poplar with large rounded scalloped leaves and brownish bark and wood

Other synonyms of black cottonwood include downy poplar, Populus heterophylla, swamp poplar.

black cottonwood (noun)	swamp cottonwood (noun)
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
North American poplar with large rounded scalloped leaves and brownish bark and wood