ventilator vs aqualung

ventilator and aqualung both are nouns.

Word	Noun	Adjective	Verb	Adverb
ventilator	Yes	No	No	No
aqualung	Yes	No	No	No

As nouns, aqualung is a hyponym of ventilator; that is, aqualung is a word with a more specific, narrower meaning than ventilator:

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

Other hyponyms of ventilator include Aqua-Lung, scuba, oxygen mask, inhalator, respirator, resuscitator, snorkel.

ventilator (noun)	aqualung (noun)
a device (such as a fan) that introduces fresh air or expels foul air	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