protuberance vs belly

protuberance and belly both are nouns.

Word	Noun	Adjective	Verb	Adverb
protuberance	Yes	No	No	No
belly	Yes	No	Yes	No

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

protuberance: something that bulges out or is protuberant or projects from its surroundings
belly: a part that bulges deeply

Other hyponyms of protuberance include frontal eminence, occipital protuberance, caput, mogul, nub, nubble, snag, wart.

protuberance (noun)	belly (noun)
something that bulges out or is protuberant or projects from its surroundings	the underpart of the body of certain vertebrates such as snakes or fish
the condition of being protuberant; the condition of bulging out	the region of the body of a vertebrate between the thorax and the pelvis
	a protruding abdomen
	the hollow inside of something
	a part that bulges deeply

protuberance (verb)	belly (verb)
	swell out or bulge out