radiator grille vs grille

radiator grille and grille both are nouns.

Word	Noun	Adjective	Verb	Adverb
radiator grille	Yes	No	No	No
grille	Yes	No	No	No

As nouns, radiator grille and grille are synonyms defined as:

radiator grille and grille: grating that admits cooling air to car's radiator

radiator grille (noun)	grille (noun)
grating that admits cooling air to car's radiator	a framework of metal bars used as a partition or a grate
	grating that admits cooling air to car's radiator
	small opening (like a window in a door) through which business can be transacted