desolation vs unhappiness

desolation and unhappiness both are nouns.

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

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

Other hypernyms of desolation include sadness.

desolation (noun)	unhappiness (noun)
an event that results in total destruction	emotions experienced when not in a state of well-being
sadness resulting from being forsaken or abandoned	state characterized by emotions ranging from mild discontentment to deep grief
the state of being decayed or destroyed
a bleak and desolate atmosphere