sourness vs ill nature

sourness and ill nature both are nouns.

Word	Noun	Adjective	Verb	Adverb
sourness	Yes	No	No	No
ill nature	Yes	No	No	No

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

sourness (noun)	ill nature (noun)
the property of being acidic	a disagreeable, irritable, or malevolent disposition
a sullen moody resentful disposition
the taste experience when vinegar or lemon juice is taken into the mouth