joke vs belly laugh

joke and belly laugh both are nouns.

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

As nouns, belly laugh is a hyponym of joke; that is, belly laugh is a word with a more specific, narrower meaning than joke:

joke (noun)	belly laugh (noun)
a ludicrous or grotesque act done for fun and amusement	a joke that seems extremely funny
activity characterized by good humor	a burst of deep loud hearty laughter
a triviality not to be taken seriously
a humorous anecdote or remark intended to provoke laughter

joke (verb)	belly laugh (verb)
act in a funny or teasing way
tell a joke; speak humorously