walkout vs work stoppage

walkout and work stoppage both are nouns.

Word	Noun	Adjective	Verb	Adverb
walkout	Yes	No	No	No
work stoppage	Yes	No	No	No

As nouns, work stoppage is a hypernym of walkout; that is, work stoppage is a word with a broader meaning than walkout:

walkout: a strike in which the workers walk out
work stoppage: a group's refusal to work in protest against low pay or bad work conditions

Other hypernyms of walkout include strike.

walkout (noun)	work stoppage (noun)
a strike in which the workers walk out	a group's refusal to work in protest against low pay or bad work conditions
the act of walking out (of a meeting or organization) as a sign of protest