gray whale vs baleen whale

gray whale and baleen whale both are nouns.

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

As nouns, baleen whale is a hypernym of gray whale; that is, baleen whale is a word with a broader meaning than gray whale:

gray whale: medium-sized greyish-black whale of the northern Pacific
baleen whale: whale with plates of whalebone along the upper jaw for filtering plankton from the water

Other hypernyms of gray whale include whalebone whale.

gray whale (noun)	baleen whale (noun)
medium-sized greyish-black whale of the northern Pacific	whale with plates of whalebone along the upper jaw for filtering plankton from the water