Greek deity vs immortal

Greek deity and immortal both are nouns.

Word	Noun	Adjective	Verb	Adverb
Greek deity	Yes	No	No	No
immortal	Yes	Yes	No	No

As nouns, immortal is a hypernym of Greek deity; that is, immortal is a word with a broader meaning than Greek deity:

Greek deity: a deity worshipped by the ancient Greeks
immortal: any supernatural being worshipped as controlling some part of the world or some aspect of life or who is the personification of a force

Other hypernyms of Greek deity include deity, divinity, god.

Greek deity (noun)	immortal (noun)
a deity worshipped by the ancient Greeks	any supernatural being worshipped as controlling some part of the world or some aspect of life or who is the personification of a force
	a person (such as an author) of enduring fame

Greek deity (adjective)	immortal (adjective)
	not subject to death