occipital protuberance vs bulge

occipital protuberance and bulge both are nouns.

Word	Noun	Adjective	Verb	Adverb
occipital protuberance	Yes	No	No	No
bulge	Yes	No	Yes	No

As nouns, bulge is a hypernym of occipital protuberance; that is, bulge is a word with a broader meaning than occipital protuberance:

occipital protuberance: prominence on the outer surface of the occipital bone
bulge: something that bulges out or is protuberant or projects from its surroundings

Other hypernyms of occipital protuberance include bump, excrescence, extrusion, gibbosity, gibbousness, hump, jut, prominence, protrusion, protuberance, swelling.

occipital protuberance (noun)	bulge (noun)
prominence on the outer surface of the occipital bone	something that bulges out or is protuberant or projects from its surroundings

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