Populus alba vs white aspen

Populus alba and white aspen both are nouns.

Word	Noun	Adjective	Verb	Adverb
Populus alba	Yes	No	No	No
white aspen	Yes	No	No	No

As nouns, Populus alba and white aspen are synonyms defined as:

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

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

Populus alba (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