mischievousness vs fun

mischievousness and fun both are nouns.

Word	Noun	Adjective	Verb	Adverb
mischievousness	Yes	No	No	No
fun	Yes	No	No	No

As nouns, fun is a hypernym of mischievousness; that is, fun is a word with a broader meaning than mischievousness:

Other hypernyms of mischievousness include playfulness.

mischievousness (noun)	fun (noun)
reckless or malicious behavior that causes discomfort or annoyance in others	activities that are enjoyable or amusing
an attribute of mischievous children	violent and excited activity
the trait of behaving like an imp	a disposition to find (or make) causes for amusement
	verbal wit or mockery (often at another's expense but not to be taken seriously)