kidney failure vs nephropathy

kidney failure and nephropathy both are nouns.

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

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

kidney failure: inability of the kidneys to excrete wastes and to help maintain the electrolyte balance
nephropathy: a disease affecting the kidneys

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

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