billy club vs billy

billy club and billy both are nouns.

Word	Noun	Adjective	Verb	Adverb
billy club	Yes	No	No	No
billy	Yes	No	No	No

As nouns, billy club and billy are synonyms defined as:

Other synonyms of billy club include baton, billystick, nightstick, truncheon.

billy club (noun)	billy (noun)
a short stout club used primarily by policemen	male goat
	a short stout club used primarily by policemen