insufficiency vs unfitness

insufficiency and unfitness both are nouns.

Word	Noun	Adjective	Verb	Adverb
insufficiency	Yes	No	No	No
unfitness	Yes	No	No	No

As nouns, unfitness is a hypernym of insufficiency; that is, unfitness is a word with a broader meaning than insufficiency:

insufficiency: (pathology) inability of a bodily part or organ to function normally
unfitness: lacking the power to perform

Other hypernyms of insufficiency include inability.

insufficiency (noun)	unfitness (noun)
lack of an adequate quantity or number	the quality of not being suitable
(pathology) inability of a bodily part or organ to function normally	lacking the power to perform
a lack of competence	poor physical condition; being out of shape or out of condition (as from a life of ease and luxury)