joke vs sidesplitter

joke and sidesplitter both are nouns.

Word	Noun	Adjective	Verb	Adverb
joke	Yes	No	Yes	No
sidesplitter	Yes	No	No	No

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

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

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