desolation vs sadness

desolation and sadness both are nouns.

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

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

Other hypernyms of desolation include unhappiness.

desolation (noun)	sadness (noun)
an event that results in total destruction	the quality of excessive mournfulness and uncheerfulness
sadness resulting from being forsaken or abandoned	emotions experienced when not in a state of well-being
the state of being decayed or destroyed	the state of being sad
a bleak and desolate atmosphere