introversion vs unsociableness

introversion and unsociableness both are nouns.

Word	Noun	Adjective	Verb	Adverb
introversion	Yes	No	No	No
unsociableness	Yes	No	No	No

As nouns, unsociableness is a hypernym of introversion; that is, unsociableness is a word with a broader meaning than introversion:

introversion: (psychology) an introverted disposition; concern with one's own thoughts and feelings
unsociableness: an unsociable disposition; avoiding friendship or companionship

Other hypernyms of introversion include unsociability.

introversion (noun)	unsociableness (noun)
(psychology) an introverted disposition; concern with one's own thoughts and feelings	an unsociable disposition; avoiding friendship or companionship
the folding in of an outer layer so as to form a pocket in the surface
the condition of being folded inward or sheathed