swamp cottonwood vs black cottonwood

swamp cottonwood and black cottonwood both are nouns.

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

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

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

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

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