extrusion vs nub

extrusion and nub both are nouns.

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

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

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

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

extrusion (noun)	nub (noun)
squeezing out by applying pressure	the choicest or most essential or most vital part of some idea or experience
something that bulges out or is protuberant or projects from its surroundings	a small piece
	a small lump or protuberance