renal failure vs kidney failure

renal failure and kidney failure both are nouns.

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

As nouns, renal failure and kidney failure are synonyms defined as:

renal failure and kidney failure: inability of the kidneys to excrete wastes and to help maintain the electrolyte balance

renal failure (noun)	kidney failure (noun)
inability of the kidneys to excrete wastes and to help maintain the electrolyte balance	inability of the kidneys to excrete wastes and to help maintain the electrolyte balance