flyer vs stuffer

flyer and stuffer both are nouns.

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

As nouns, stuffer is a hyponym of flyer; that is, stuffer is a word with a more specific, narrower meaning than flyer:

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

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