folly vs absurdity

folly and absurdity both are nouns.

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

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

Other hyponyms of folly include indiscretion, injudiciousness, fatuity, fatuousness, silliness, asininity.

folly (noun)	absurdity (noun)
foolish or senseless behavior	a ludicrous folly
a stupid mistake	a message whose content is at variance with reason
the trait of acting stupidly or rashly
the quality of being rash and foolish