emergency brake vs emergency

emergency brake and emergency both are nouns.

Word	Noun	Adjective	Verb	Adverb
emergency brake	Yes	No	No	No
emergency	Yes	No	No	No

As nouns, emergency brake and emergency are synonyms defined as:

emergency brake and emergency: a brake operated by hand; usually operates by mechanical linkage

Other synonyms of emergency brake include hand brake, parking brake.

emergency brake (noun)	emergency (noun)
a brake operated by hand; usually operates by mechanical linkage	a brake operated by hand; usually operates by mechanical linkage
	a sudden unforeseen crisis (usually involving danger) that requires immediate action
	a state in which martial law applies