japery vs folly

japery and folly both are nouns.

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

As nouns, folly is a hypernym of japery; that is, folly is a word with a broader meaning than japery:

Other hypernyms of japery include craziness, foolery, indulgence, lunacy, tomfoolery.

japery (noun)	folly (noun)
acting like a clown or buffoon	foolish or senseless behavior
	a stupid mistake
	the trait of acting stupidly or rashly
	the quality of being rash and foolish