American grey birch vs grey birch

American grey birch and grey birch both are nouns.

Word	Noun	Adjective	Verb	Adverb
American grey birch	Yes	No	No	No
grey birch	Yes	No	No	No

As nouns, American grey birch and grey birch are synonyms defined as:

American grey birch and grey birch: medium-sized birch of eastern North America having white or pale grey bark and valueless wood; occurs often as a second-growth forest tree

Other synonyms of American grey birch include American gray birch, Betula populifolia, gray birch.

American grey birch (noun)	grey birch (noun)
medium-sized birch of eastern North America having white or pale grey bark and valueless wood; occurs often as a second-growth forest tree	medium-sized birch of eastern North America having white or pale grey bark and valueless wood; occurs often as a second-growth forest tree