airliner vs airplane

airliner and airplane both are nouns.

Word	Noun	Adjective	Verb	Adverb
airliner	Yes	No	No	No
airplane	Yes	No	No	No

As nouns, airplane is a hypernym of airliner; that is, airplane is a word with a broader meaning than airliner:

airliner: a commercial airplane that carries passengers
airplane: an aircraft that has a fixed wing and is powered by propellers or jets

Other hypernyms of airliner include aeroplane, plane.

airliner (noun)	airplane (noun)
a commercial airplane that carries passengers	an aircraft that has a fixed wing and is powered by propellers or jets