stuffer vs flier

stuffer and flier both are nouns.

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

As nouns, flier is a hypernym of stuffer; that is, flier is a word with a broader meaning than stuffer:

stuffer: an advertising circular that is enclosed with other material and (usually) sent by mail
flier: an advertisement (usually printed on a page or in a leaflet) intended for wide distribution

Other hypernyms of stuffer include bill, broadsheet, broadside, circular, flyer, handbill, throwaway.

stuffer (noun)	flier (noun)
an advertising circular that is enclosed with other material and (usually) sent by mail	an advertisement (usually printed on a page or in a leaflet) intended for wide distribution
a craftsman who stuffs and mounts the skins of animals for display	someone who travels by air
	someone who operates an aircraft