solitariness vs isolation

solitariness and isolation both are nouns.

Word	Noun	Adjective	Verb	Adverb
solitariness	Yes	No	No	No
isolation	Yes	No	No	No

As nouns, isolation is a hypernym of solitariness; that is, isolation is a word with a broader meaning than solitariness:

solitariness (noun)	isolation (noun)
a disposition toward being alone	the act of isolating something; setting something apart from others
the state of being alone in solitary isolation	a country's withdrawal from international politics
	a feeling of being disliked and alone
	(psychiatry) a defense mechanism in which memory of an unacceptable act or impulse is separated from the emotion originally associated with it
	a state of separation between persons or groups