publicity vs advert

publicity and advert both are nouns.

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

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

publicity: a message issued in behalf of some product or cause or idea or person or institution
advert: a public promotion of some product or service

publicity (noun)	advert (noun)
the quality of being open to public view	a public promotion of some product or service
a message issued in behalf of some product or cause or idea or person or institution

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