acerbity vs sourness

acerbity and sourness both are nouns.

Word	Noun	Adjective	Verb	Adverb
acerbity	Yes	No	No	No
sourness	Yes	No	No	No

As nouns, sourness is a hypernym of acerbity; that is, sourness is a word with a broader meaning than acerbity:

Other hypernyms of acerbity include acidity, sour.

acerbity (noun)	sourness (noun)
a rough and bitter manner	the property of being acidic
a sharp sour taste	a sullen moody resentful disposition
a sharp bitterness	the taste experience when vinegar or lemon juice is taken into the mouth