African grey vs African gray

African grey and African gray both are nouns.

Word	Noun	Adjective	Verb	Adverb
African grey	Yes	No	No	No
African gray	Yes	No	No	No

As nouns, African grey and African gray are synonyms defined as:

African grey and African gray: commonly domesticated grey parrot with red-and-black tail and white face; native to equatorial Africa

Other synonyms of African grey include Psittacus erithacus.

African grey (noun)	African gray (noun)
commonly domesticated grey parrot with red-and-black tail and white face; native to equatorial Africa	commonly domesticated grey parrot with red-and-black tail and white face; native to equatorial Africa