escape cock vs relief valve

escape cock and relief valve both are nouns.

Word	Noun	Adjective	Verb	Adverb
escape cock	Yes	No	No	No
relief valve	Yes	No	No	No

As nouns, escape cock and relief valve are synonyms defined as:

escape cock and relief valve: a valve in a container in which pressure can build up (as a steam boiler); it opens automatically when the pressure reaches a dangerous level

Other synonyms of escape cock include escape, escape valve, safety valve.

escape cock (noun)	relief valve (noun)
a valve in a container in which pressure can build up (as a steam boiler); it opens automatically when the pressure reaches a dangerous level	a valve in a container in which pressure can build up (as a steam boiler); it opens automatically when the pressure reaches a dangerous level