roulette vs gambling game

roulette and gambling game both are nouns.

Word	Noun	Adjective	Verb	Adverb
roulette	Yes	No	No	No
gambling game	Yes	No	No	No

As nouns, gambling game is a hypernym of roulette; that is, gambling game is a word with a broader meaning than roulette:

roulette: a gambling game in which players bet on which compartment of a revolving wheel a small ball will come to rest in
gambling game: a game that involves gambling

Other hypernyms of roulette include game of chance.

roulette (noun)	gambling game (noun)
a gambling game in which players bet on which compartment of a revolving wheel a small ball will come to rest in	a game that involves gambling
a wheel with teeth for making a row of perforations
a line generated by a point on one figure rolling around a second figure