unworthiness vs ineptness

unworthiness and ineptness both are nouns.

Word	Noun	Adjective	Verb	Adverb
unworthiness	Yes	No	No	No
ineptness	Yes	No	No	No

As nouns, ineptness is a hypernym of unworthiness; that is, ineptness is a word with a broader meaning than unworthiness:

unworthiness: the quality of being not particularly suitable or befitting
ineptness: the quality of having the wrong properties for a specific purpose

Other hypernyms of unworthiness include unsuitability, unsuitableness.

unworthiness (noun)	ineptness (noun)
the quality or state of lacking merit or value	the quality of having the wrong properties for a specific purpose
the quality of being not particularly suitable or befitting	unskillfulness resulting from a lack of training