swamp poplar vs swamp cottonwood

swamp poplar and swamp cottonwood both are nouns.

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

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

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

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

swamp poplar (noun)	swamp cottonwood (noun)
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