nub vs swelling

nub and swelling both are nouns.

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

As nouns, swelling is a hypernym of nub; that is, swelling is a word with a broader meaning than nub:

nub: a small lump or protuberance
swelling: something that bulges out or is protuberant or projects from its surroundings

nub (noun)	swelling (noun)
the choicest or most essential or most vital part of some idea or experience	the increase in volume of certain substances when they are heated (often accompanied by release of water)
a small piece	something that bulges out or is protuberant or projects from its surroundings
a small lump or protuberance	an abnormal protuberance or localized enlargement