airway vs breather

airway and breather both are nouns.

Word	Noun	Adjective	Verb	Adverb
airway	Yes	No	No	No
breather	Yes	No	No	No

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

airway: a duct that provides ventilation (as in mines)
breather: air passage provided by a retractable device containing intake and exhaust pipes; permits a submarine to stay submerged for extended periods of time

Other hyponyms of airway include register, schnorchel, schnorkel, snorkel, snorkel breather, upcast, ventilation shaft.

airway (noun)	breather (noun)
a commercial enterprise that provides scheduled flights for passengers	air passage provided by a retractable device containing intake and exhaust pipes; permits a submarine to stay submerged for extended periods of time
a duct that provides ventilation (as in mines)	a short respite
the passages through which air enters and leaves the body
a designated route followed by airplanes in flying from one airport to another