walk out vs protest

walk out is not a noun while protest is a noun.

Word	Noun	Adjective	Verb	Adverb
walk out	No	No	Yes	No
protest	Yes	No	Yes	No

As verbs, protest is a hypernym of walk out; that is, protest is a word with a broader meaning than walk out:

Other hypernyms of walk out include dissent, resist.

walk out (noun)	protest (noun)
	the act of protesting; a public (often organized) manifestation of dissent
	a formal and solemn declaration of objection
	the act of making a strong public expression of disagreement and disapproval

walk out (verb)	protest (verb)
leave suddenly, often as an expression of disapproval	utter words of protest
leave abruptly, often in protest or anger	affirm or avow formally or solemnly
stop work in order to press demands	express opposition through action or words