Poseidon vs Greek mythology

Poseidon and Greek mythology both are nouns.

Word	Noun	Adjective	Verb	Adverb
Poseidon	Yes	No	No	No
Greek mythology	Yes	No	No	No

Poseidon (noun)	Greek mythology (noun)
(Greek mythology) the god of the sea and earthquakes in ancient mythology; brother of Zeus and Hades and Hera; identified with Roman Neptune	the mythology of the ancient Greeks