breathing device vs breathing apparatus

breathing device and breathing apparatus both are nouns.

Word	Noun	Adjective	Verb	Adverb
breathing device	Yes	No	No	No
breathing apparatus	Yes	No	No	No

As nouns, breathing device and breathing apparatus are synonyms defined as:

breathing device and breathing apparatus: a device that facilitates breathing in cases of respiratory failure

Other synonyms of breathing device include breathing machine, ventilator.

breathing device (noun)	breathing apparatus (noun)
a device that facilitates breathing in cases of respiratory failure	a device that facilitates breathing in cases of respiratory failure