narwhal vs whale

narwhal and whale both are nouns.

Word	Noun	Adjective	Verb	Adverb
narwhal	Yes	No	No	No
whale	Yes	No	Yes	No

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

narwhal: small Arctic whale the male having a long spiral ivory tusk
whale: any of the larger cetacean mammals having a streamlined body and breathing through a blowhole on the head

narwhal (noun)	whale (noun)
small Arctic whale the male having a long spiral ivory tusk	any of the larger cetacean mammals having a streamlined body and breathing through a blowhole on the head
	a very large person; impressive in size or qualities

narwhal (verb)	whale (verb)
	hunt for whales