silver birch vs common birch

silver birch and common birch both are nouns.

Word	Noun	Adjective	Verb	Adverb
silver birch	Yes	No	No	No
common birch	Yes	No	No	No

As nouns, silver birch and common birch are synonyms defined as:

silver birch and common birch: European birch with silvery white peeling bark and markedly drooping branches

Other synonyms of silver birch include Betula pendula, European white birch.

silver birch (noun)	common birch (noun)
European birch with silvery white peeling bark and markedly drooping branches	European birch with silvery white peeling bark and markedly drooping branches