failing vs flaw

failing and flaw both are nouns.

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

As nouns, flaw is a hyponym of failing; that is, flaw is a word with a more specific, narrower meaning than failing:

Other hyponyms of failing include inadequacy, insufficiency, fatigue.

failing (noun)	flaw (noun)
failure to reach a minimum required performance	an imperfection in an object or machine
a flaw or weak point	defect or weakness in a person's character
	an imperfection in a plan or theory or legal document that causes it to fail or that reduces its effectiveness

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

failing (verb)	flaw (verb)
	add a flaw or blemish to; make imperfect or defective