aqualung vs breathing machine

aqualung and breathing machine both are nouns.

Word	Noun	Adjective	Verb	Adverb
aqualung	Yes	No	No	No
breathing machine	Yes	No	No	No

As nouns, breathing machine is a hypernym of aqualung; that is, breathing machine is a word with a broader meaning than aqualung:

aqualung: a device (trade name Aqua-Lung) that lets divers breathe under water; scuba is an acronym for self-contained underwater breathing apparatus
breathing machine: a device that facilitates breathing in cases of respiratory failure

Other hypernyms of aqualung include breathing apparatus, breathing device, ventilator.

aqualung (noun)	breathing machine (noun)
a device (trade name Aqua-Lung) that lets divers breathe under water; scuba is an acronym for self-contained underwater breathing apparatus	a device that facilitates breathing in cases of respiratory failure