insufficiency vs failing

insufficiency and failing both are nouns.

Word	Noun	Adjective	Verb	Adverb
insufficiency	Yes	No	No	No
failing	Yes	Yes	No	No

As nouns, failing is a hypernym of insufficiency; that is, failing is a word with a broader meaning than insufficiency:

Other hypernyms of insufficiency include weakness.

insufficiency (noun)	failing (noun)
lack of an adequate quantity or number	failure to reach a minimum required performance
(pathology) inability of a bodily part or organ to function normally	a flaw or weak point
a lack of competence

insufficiency (adjective)	failing (adjective)
	below acceptable in performance