folly vs frivolity

folly and frivolity both are nouns.

Word	Noun	Adjective	Verb	Adverb
folly	Yes	No	No	No
frivolity	Yes	No	No	No

As nouns, frivolity is a hyponym of folly; that is, frivolity is a word with a more specific, narrower meaning than folly:

Other hyponyms of folly include meshugaas, mishegaas, mishegoss, buffoonery, clowning, harlequinade, japery, prank.

folly (noun)	frivolity (noun)
foolish or senseless behavior	acting like a clown or buffoon
a stupid mistake	something of little value or significance
the trait of acting stupidly or rashly	the trait of being frivolous; not serious or sensible
the quality of being rash and foolish