Greek mythology vs Iapetus

Greek mythology and Iapetus both are nouns.

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

Greek mythology (noun)	Iapetus (noun)
the mythology of the ancient Greeks	(Greek mythology) the Titan who was father of Atlas and Epimetheus and Prometheus in ancient mythology