wittiness vs humorousness

wittiness and humorousness both are nouns.

Word	Noun	Adjective	Verb	Adverb
wittiness	Yes	No	No	No
humorousness	Yes	No	No	No

As nouns, humorousness is a hypernym of wittiness; that is, humorousness is a word with a broader meaning than wittiness:

Other hypernyms of wittiness include jocoseness, jocosity, merriness.

wittiness (noun)	humorousness (noun)
The quality of being clever, amusingly ingenious.	the trait of merry joking
a message whose ingenuity or verbal skill or incongruity has the power to evoke laughter