incompetent vs inept

incompetent is a noun but inept is not a noun.

Word	Noun	Adjective	Verb	Adverb
incompetent	Yes	Yes	No	No
inept	No	Yes	No	No

incompetent (noun)	inept (noun)
someone who is not competent to take effective action

incompetent (adjective)	inept (adjective)
not qualified or suited for a purpose	generally incompetent and ineffectual
legally not qualified or sufficient	not elegant or graceful in expression
not doing a good job	revealing lack of perceptiveness or judgment or finesse
not meeting requirements
showing lack of skill or aptitude