flyer vs circular

flyer and circular both are nouns.

Word	Noun	Adjective	Verb	Adverb
flyer	Yes	No	No	No
circular	Yes	Yes	No	No

As nouns, flyer and circular are synonyms defined as:

flyer and circular: an advertisement (usually printed on a page or in a leaflet) intended for wide distribution

Other synonyms of flyer include bill, broadsheet, broadside, flier, handbill, throwaway.

flyer (noun)	circular (noun)
an advertisement (usually printed on a page or in a leaflet) intended for wide distribution	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

flyer (adjective)	circular (adjective)
	having the shape or form of a circle
	describing a circle; moving in a circle