incompetent vs incapable

incompetent is a noun but incapable is not a noun.

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

As adjectives, incompetent and incapable are synonyms defined as:

Other synonyms of incompetent include unequal to.

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

incompetent (adjective)	incapable (adjective)
not qualified or suited for a purpose	(followed by `of') lacking capacity or ability
legally not qualified or sufficient	(followed by `of') not having the temperament or inclination for
not doing a good job	not meeting requirements
not meeting requirements	not being susceptible to or admitting of something (usually followed by `of')
showing lack of skill or aptitude