flier vs airplane pilot

flier and airplane pilot both are nouns.

Word	Noun	Adjective	Verb	Adverb
flier	Yes	No	No	No
airplane pilot	Yes	No	No	No

As nouns, airplane pilot is a hyponym of flier; that is, airplane pilot is a word with a more specific, narrower meaning than flier:

Other hyponyms of flier include airwoman, aviatress, aviatrix, pilot, airman.

flier (noun)	airplane pilot (noun)
an advertisement (usually printed on a page or in a leaflet) intended for wide distribution	someone who is licensed to operate an aircraft in flight
someone who travels by air
someone who operates an aircraft