swelling vs snag

swelling and snag both are nouns.

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

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

swelling: something that bulges out or is protuberant or projects from its surroundings
snag: a sharp protuberance

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

swelling (noun)	snag (noun)
the increase in volume of certain substances when they are heated (often accompanied by release of water)	an unforeseen obstacle
something that bulges out or is protuberant or projects from its surroundings	an opening made forcibly as by pulling apart
an abnormal protuberance or localized enlargement	a dead tree that is still standing, usually in an undisturbed forest
	a sharp protuberance

swelling (verb)	snag (verb)
	catch on a snag
	hew jaggedly
	get by acting quickly and smartly