emergency vs emergency brake

emergency and emergency brake both are nouns.

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

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

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

Other synonyms of emergency include hand brake, parking brake.

emergency (noun)	emergency brake (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