circular vs advert

circular and advert both are nouns.

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

As nouns, advert is a hypernym of circular; that is, advert is a word with a broader meaning than circular:

circular: an advertisement (usually printed on a page or in a leaflet) intended for wide distribution
advert: a public promotion of some product or service

Other hypernyms of circular include ad, advertisement, advertising, advertizement, advertizing.

circular (noun)	advert (noun)
an advertisement (usually printed on a page or in a leaflet) intended for wide distribution	a public promotion of some product or service

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

circular (verb)	advert (verb)
	make a more or less disguised reference to
	make reference to
	give heed (to)