mischievousness vs mischief

mischievousness and mischief both are nouns.

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

As nouns, mischievousness and mischief are synonyms defined as:

mischievousness and mischief: reckless or malicious behavior that causes discomfort or annoyance in others

Other synonyms of mischievousness include devilment, devilry, deviltry, mischief-making, rascality, roguery, roguishness, shenanigan.

mischievousness (noun)	mischief (noun)
reckless or malicious behavior that causes discomfort or annoyance in others	reckless or malicious behavior that causes discomfort or annoyance in others
an attribute of mischievous children	the quality or nature of being harmful or evil
the trait of behaving like an imp