advert vs promo

advert and promo both are nouns.

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

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

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

Other hypernyms of advert include packaging, promotion, promotional material, publicity.

advert (noun)	promo (noun)
a public promotion of some product or service	a message issued in behalf of some product or cause or idea or person or institution

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