advertising vs ad

advertising and ad both are nouns.

Word	Noun	Adjective	Verb	Adverb
advertising	Yes	No	No	No
ad	Yes	No	No	No

As nouns, advertising and ad are synonyms defined as:

Other synonyms of advertising include advert, advertisement, advertizement, advertizing.

advertising (noun)	ad (noun)
the business of drawing public attention to goods and services	a public promotion of some product or service
a public promotion of some product or service