speckled alder vs Alnus rugosa

speckled alder and Alnus rugosa both are nouns.

Word	Noun	Adjective	Verb	Adverb
speckled alder	Yes	No	No	No
Alnus rugosa	Yes	No	No	No

As nouns, speckled alder and Alnus rugosa are synonyms defined as:

speckled alder and Alnus rugosa: common shrub of Canada and northeastern United States having shoots scattered with rust-colored down

speckled alder (noun)	Alnus rugosa (noun)
common shrub of Canada and northeastern United States having shoots scattered with rust-colored down	common shrub of Canada and northeastern United States having shoots scattered with rust-colored down