illiteracy vs inability

illiteracy and inability both are nouns.

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

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

illiteracy (noun)	inability (noun)
an inability to read	lacking the power to perform
ignorance resulting from not reading	lack of ability (especially mental ability) to do something