top billing vs advertising

top billing and advertising both are nouns.

Word	Noun	Adjective	Verb	Adverb
top billing	Yes	No	No	No
advertising	Yes	No	No	No

As nouns, advertising is a hypernym of top billing; that is, advertising is a word with a broader meaning than top billing:

top billing: the advertisement of a star's name at the top of a theatrical poster
advertising: a public promotion of some product or service

Other hypernyms of top billing include ad, advert, advertisement, advertizement, advertizing.

top billing (noun)	advertising (noun)
the advertisement of a star's name at the top of a theatrical poster	the business of drawing public attention to goods and services
	a public promotion of some product or service