sarcasm vs wittiness

sarcasm and wittiness both are nouns.

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

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

sarcasm: witty language used to convey insults or scorn
wittiness: a message whose ingenuity or verbal skill or incongruity has the power to evoke laughter

Other hypernyms of sarcasm include humor, humour, wit, witticism.

sarcasm (noun)	wittiness (noun)
witty language used to convey insults or scorn	The quality of being clever, amusingly ingenious.
	a message whose ingenuity or verbal skill or incongruity has the power to evoke laughter