folly vs lunacy

folly and lunacy both are nouns.

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

As nouns, folly and lunacy are synonyms defined as:

Other synonyms of folly include craziness, foolery, indulgence, tomfoolery.

folly (noun)	lunacy (noun)
foolish or senseless behavior	foolish or senseless behavior
a stupid mistake	obsolete terms for legal insanity
the trait of acting stupidly or rashly
the quality of being rash and foolish