aspen poplar vs white aspen

aspen poplar and white aspen both are nouns.

Word	Noun	Adjective	Verb	Adverb
aspen poplar	Yes	No	No	No
white aspen	Yes	No	No	No

As nouns, aspen poplar and white aspen are synonyms defined as:

aspen poplar and white aspen: a poplar that is widely cultivated in the United States; has white bark and leaves with whitish undersurfaces

Other synonyms of aspen poplar include abele, Populus alba, silver-leaved poplar, white poplar.

aspen poplar (noun)	white aspen (noun)
a poplar that is widely cultivated in the United States; has white bark and leaves with whitish undersurfaces	a poplar that is widely cultivated in the United States; has white bark and leaves with whitish undersurfaces