renal failure vs failure

renal failure and failure both are nouns.

Word	Noun	Adjective	Verb	Adverb
renal failure	Yes	No	No	No
failure	Yes	No	No	No

As nouns, failure is a hypernym of renal failure; that is, failure is a word with a broader meaning than renal failure:

renal failure: inability of the kidneys to excrete wastes and to help maintain the electrolyte balance
failure: loss of ability to function normally

Other hypernyms of renal failure include kidney disease, nephropathy, nephrosis, renal disorder.

renal failure (noun)	failure (noun)
inability of the kidneys to excrete wastes and to help maintain the electrolyte balance	an act that fails
	an unexpected omission
	an event that does not accomplish its intended purpose
	a person with a record of failing; someone who loses consistently
	lack of success
	loss of ability to function normally
	inability to discharge all your debts as they come due