belly laugh vs sidesplitter

belly laugh and sidesplitter both are nouns.

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

As nouns, belly laugh and sidesplitter are synonyms defined as:

Other synonyms of belly laugh include howler, riot, scream, thigh-slapper, wow.

belly laugh (noun)	sidesplitter (noun)
a joke that seems extremely funny	a joke that seems extremely funny
a burst of deep loud hearty laughter