kidney-shaped vs reniform

kidney-shaped and reniform both are adjectives.

Word	Noun	Adjective	Verb	Adverb
kidney-shaped	No	Yes	No	No
reniform	No	Yes	No	No

As adjectives, kidney-shaped and reniform are synonyms defined as:

kidney-shaped and reniform: (of a leaf or bean shape) resembling the shape of kidney

kidney-shaped (adjective)	reniform (adjective)
(of a leaf or bean shape) resembling the shape of kidney	(of a leaf or bean shape) resembling the shape of kidney