hazel alder vs smooth alder

hazel alder and smooth alder both are nouns.

Word	Noun	Adjective	Verb	Adverb
hazel alder	Yes	No	No	No
smooth alder	Yes	No	No	No

As nouns, hazel alder and smooth alder are synonyms defined as:

hazel alder and smooth alder: common shrub of the eastern United States with smooth bark

Other synonyms of hazel alder include Alnus serrulata.

hazel alder (noun)	smooth alder (noun)
common shrub of the eastern United States with smooth bark	common shrub of the eastern United States with smooth bark