button ad vs advert

button ad and advert both are nouns.

Word	Noun	Adjective	Verb	Adverb
button ad	Yes	No	No	No
advert	Yes	No	Yes	No

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

button ad: small circular, rectangular, or square advertisement appearing usually at the bottom of a webpage.
advert: a public promotion of some product or service

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

button ad (noun)	advert (noun)
small circular, rectangular, or square advertisement appearing usually at the bottom of a webpage.	a public promotion of some product or service

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