grey whale vs gray whale

grey whale and gray whale both are nouns.

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

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

grey whale and gray whale: medium-sized greyish-black whale of the northern Pacific

Other synonyms of grey whale include devilfish, Eschrichtius gibbosus, Eschrichtius robustus.

grey whale (noun)	gray whale (noun)
medium-sized greyish-black whale of the northern Pacific	medium-sized greyish-black whale of the northern Pacific