Olympic Games vs agon

Olympic Games and agon both are nouns.

Word	Noun	Adjective	Verb	Adverb
Olympic Games	Yes	No	No	No
agon	Yes	No	No	No

As nouns, agon is a hypernym of Olympic Games; that is, agon is a word with a broader meaning than Olympic Games:

Olympic Games: the ancient Panhellenic celebration at Olympia in honor of Zeus; held every 4 years beginning in 776 BC
agon: a festivity in ancient Greece at which competitors contended for prizes

Olympic Games (noun)	agon (noun)
the ancient Panhellenic celebration at Olympia in honor of Zeus; held every 4 years beginning in 776 BC	a festivity in ancient Greece at which competitors contended for prizes
the modern revival of the ancient games held once every 4 years in a selected country