ventilator vs Aqua-Lung

ventilator and Aqua-Lung both are nouns.

Word	Noun	Adjective	Verb	Adverb
ventilator	Yes	No	No	No
Aqua-Lung	Yes	No	No	No

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

ventilator: a device that facilitates breathing in cases of respiratory failure
Aqua-Lung: 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 aqualung, scuba, oxygen mask, inhalator, respirator, resuscitator, snorkel.

ventilator (noun)	Aqua-Lung (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