gray whale vs grey whale

gray whale and grey whale both are nouns.

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

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

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

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

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