bulge vs belly

bulge and belly both are nouns.

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

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

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

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

bulge (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 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

bulge (verb)	belly (verb)
swell or protrude outwards	swell out or bulge out
cause to bulge or swell outwards
bulge outward
bulge out; form a bulge outward, or be so full as to appear to bulge