sourness vs sullenness

sourness and sullenness both are nouns.

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

As nouns, sourness and sullenness are synonyms defined as:

Other synonyms of sourness include moroseness, sulkiness.

sourness (noun)	sullenness (noun)
the property of being acidic	a sullen moody resentful disposition
a sullen moody resentful disposition	a gloomy ill-tempered feeling
the taste experience when vinegar or lemon juice is taken into the mouth