emergency vs parking brake

emergency and parking brake both are nouns.

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

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

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

Other synonyms of emergency include emergency brake, hand brake.

emergency (noun)	parking 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