imbecility vs betise

imbecility and betise both are nouns.

Word	Noun	Adjective	Verb	Adverb
imbecility	Yes	No	No	No
betise	Yes	No	No	No

As nouns, imbecility and betise are synonyms defined as:

Other synonyms of imbecility include folly, foolishness, stupidity.

imbecility (noun)	betise (noun)
a stupid mistake	a stupid mistake
retardation more severe than a moron but not as severe as an idiot