nightstick vs billystick

nightstick and billystick both are nouns.

Word	Noun	Adjective	Verb	Adverb
nightstick	Yes	No	No	No
billystick	Yes	No	No	No

As nouns, nightstick and billystick are synonyms defined as:

nightstick and billystick: a short stout club used primarily by policemen

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

nightstick (noun)	billystick (noun)
a short stout club used primarily by policemen	a short stout club used primarily by policemen