frivolousness vs levity

frivolousness and levity both are nouns.

Word	Noun	Adjective	Verb	Adverb
frivolousness	Yes	No	No	No
levity	Yes	No	No	No

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

Other hyponyms of frivolousness include giddiness, silliness, fun, playfulness.

frivolousness (noun)	levity (noun)
the trait of being frivolous; not serious or sensible	a manner lacking seriousness
	feeling an inappropriate lack of seriousness