harmoniousness vs compatibility

harmoniousness and compatibility both are nouns.

Word	Noun	Adjective	Verb	Adverb
harmoniousness	Yes	No	No	No
compatibility	Yes	No	No	No

As nouns, compatibility is a hypernym of harmoniousness; that is, compatibility is a word with a broader meaning than harmoniousness:

harmoniousness: compatibility in opinion and action
compatibility: capability of existing or performing in harmonious or congenial combination

harmoniousness (noun)	compatibility (noun)
compatibility in opinion and action	capability of existing or performing in harmonious or congenial combination
the property of sounding harmonious	a feeling of sympathetic understanding