Olympic god vs Olympian

Olympic god and Olympian both are nouns.

Word	Noun	Adjective	Verb	Adverb
Olympic god	Yes	No	No	No
Olympian	Yes	Yes	No	No

As nouns, Olympic god and Olympian are synonyms defined as:

Olympic god and Olympian: a classical Greek god after the overthrow of the Titans

Other synonyms of Olympic god include Twelve Olympians.

Olympic god (noun)	Olympian (noun)
a classical Greek god after the overthrow of the Titans	an athlete who participates in the Olympic games
	a classical Greek god after the overthrow of the Titans

Olympic god (adjective)	Olympian (adjective)
	of or pertaining to the greater gods of ancient Greece whose abode was Mount Olympus
	of the region of Olympia in Greece or its inhabitants