ad vs promotion

ad and promotion both are nouns.

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

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

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

Other hypernyms of ad include packaging, promo, promotional material, publicity.

ad (noun)	promotion (noun)
a public promotion of some product or service	act of raising in rank or position
	the advancement of some enterprise
	a message issued in behalf of some product or cause or idea or person or institution
	encouragement of the progress or growth or acceptance of something