renal failure vs nephropathy

renal failure and nephropathy both are nouns.

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

As nouns, nephropathy is a hypernym of renal failure; that is, nephropathy 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
nephropathy: a disease affecting the kidneys

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

renal failure (noun)	nephropathy (noun)
inability of the kidneys to excrete wastes and to help maintain the electrolyte balance	a disease affecting the kidneys