swelling vs belly

swelling and belly both are nouns.

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

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

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

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

swelling (noun)	belly (noun)
the increase in volume of certain substances when they are heated (often accompanied by release of water)	the underpart of the body of certain vertebrates such as snakes or fish
something that bulges out or is protuberant or projects from its surroundings	the region of the body of a vertebrate between the thorax and the pelvis
an abnormal protuberance or localized enlargement	a protruding abdomen
	the hollow inside of something
	a part that bulges deeply

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