protest vs walk out

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

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

As verbs, walk out is a hyponym of protest; that is, walk out is a word with a more specific, narrower meaning than protest:

Other hyponyms of protest include strike, demonstrate, march, arise, rebel, rise, rise up, rebel, renegade.

protest (noun)	walk out (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

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