common alder vs European black alder

common alder and European black alder both are nouns.

Word	Noun	Adjective	Verb	Adverb
common alder	Yes	No	No	No
European black alder	Yes	No	No	No

As nouns, common alder and European black alder are synonyms defined as:

common alder and European black alder: medium-sized tree with brown-black bark and woody fruiting catkins; leaves are hairy beneath

Other synonyms of common alder include Alnus glutinosa, Alnus vulgaris.

common alder (noun)	European black alder (noun)
medium-sized tree with brown-black bark and woody fruiting catkins; leaves are hairy beneath	medium-sized tree with brown-black bark and woody fruiting catkins; leaves are hairy beneath