fun vs sauciness

fun and sauciness both are nouns.

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

As nouns, sauciness is a hyponym of fun; that is, sauciness is a word with a more specific, narrower meaning than fun:

fun (noun)	sauciness (noun)
activities that are enjoyable or amusing	inappropriate playfulness
violent and excited activity
a disposition to find (or make) causes for amusement
verbal wit or mockery (often at another's expense but not to be taken seriously)