fatuousness vs silliness

fatuousness and silliness both are nouns.

Word	Noun	Adjective	Verb	Adverb
fatuousness	Yes	No	No	No
silliness	Yes	No	No	No

As nouns, fatuousness and silliness are synonyms defined as:

Other synonyms of fatuousness include absurdity, fatuity.

fatuousness (noun)	silliness (noun)
a ludicrous folly	a ludicrous folly
	an impulsive scatterbrained manner