dolefulness vs unhappiness

dolefulness and unhappiness both are nouns.

Word	Noun	Adjective	Verb	Adverb
dolefulness	Yes	No	No	No
unhappiness	Yes	No	No	No

As nouns, unhappiness is a hypernym of dolefulness; that is, unhappiness is a word with a broader meaning than dolefulness:

Other hypernyms of dolefulness include sadness.

dolefulness (noun)	unhappiness (noun)
sadness caused by grief or affliction	emotions experienced when not in a state of well-being
	state characterized by emotions ranging from mild discontentment to deep grief