aviator vs flier

aviator and flier both are nouns.

Word	Noun	Adjective	Verb	Adverb
aviator	Yes	No	No	No
flier	Yes	No	No	No

As nouns, aviator and flier are synonyms defined as:

Other synonyms of aviator include aeronaut, flyer.

aviator (noun)	flier (noun)
someone who operates an aircraft	an advertisement (usually printed on a page or in a leaflet) intended for wide distribution
	someone who travels by air
	someone who operates an aircraft