belly laugh vs gag

belly laugh and gag both are nouns.

Word	Noun	Adjective	Verb	Adverb
belly laugh	Yes	No	No	No
gag	Yes	No	Yes	No

As nouns, gag is a hypernym of belly laugh; that is, gag is a word with a broader meaning than belly laugh:

Other hypernyms of belly laugh include jape, jest, joke, laugh.

belly laugh (noun)	gag (noun)
a joke that seems extremely funny	restraint put into a person's mouth to prevent speaking or shouting
a burst of deep loud hearty laughter	a humorous anecdote or remark intended to provoke laughter

belly laugh (verb)	gag (verb)
	struggle for breath; have insufficient oxygen intake
	make an unsuccessful effort to vomit; strain to vomit
	cause to retch or choke
	make jokes or quips
	be too tight; rub or press
	tie a gag around someone's mouth in order to silence them
	prevent from speaking out