inability vs knowledge

inability and knowledge both are nouns.

Word	Noun	Adjective	Verb	Adverb
inability	Yes	No	No	No
knowledge	Yes	No	No	No

As nouns, knowledge is a hypernym of inability; that is, knowledge is a word with a broader meaning than inability:

inability: lack of ability (especially mental ability) to do something
knowledge: the psychological result of perception and learning and reasoning

Other hypernyms of inability include cognition, noesis.

inability (noun)	knowledge (noun)
lacking the power to perform	the psychological result of perception and learning and reasoning
lack of ability (especially mental ability) to do something