unpleasantness vs painfulness

unpleasantness and painfulness both are nouns.

Word	Noun	Adjective	Verb	Adverb
unpleasantness	Yes	No	No	No
painfulness	Yes	No	No	No

As nouns, painfulness is a hypernym of unpleasantness; that is, painfulness is a word with a broader meaning than unpleasantness:

unpleasantness: the feeling caused by disagreeable stimuli; one pole of a continuum of states of feeling
painfulness: emotional distress; a fundamental feeling that people try to avoid

Other hypernyms of unpleasantness include pain.

unpleasantness (noun)	painfulness (noun)
the quality of giving displeasure	the quality of being painful
the feeling caused by disagreeable stimuli; one pole of a continuum of states of feeling	emotional distress; a fundamental feeling that people try to avoid