sit-down strike vs sit-down

sit-down strike and sit-down both are nouns.

Word	Noun	Adjective	Verb	Adverb
sit-down strike	Yes	No	No	No
sit-down	Yes	No	No	No

As nouns, sit-down strike and sit-down are synonyms defined as:

sit-down strike and sit-down: a strike in which workers refuse to leave the workplace until a settlement is reached

sit-down strike (noun)	sit-down (noun)
a strike in which workers refuse to leave the workplace until a settlement is reached	a strike in which workers refuse to leave the workplace until a settlement is reached