sales promotion vs publicity

sales promotion and publicity both are nouns.

Word	Noun	Adjective	Verb	Adverb
sales promotion	Yes	No	No	No
publicity	Yes	No	No	No

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

sales promotion: promotion that supplements or coordinates advertising
publicity: a message issued in behalf of some product or cause or idea or person or institution

Other hypernyms of sales promotion include packaging, promo, promotion, promotional material.

sales promotion (noun)	publicity (noun)
promotion that supplements or coordinates advertising	the quality of being open to public view
	a message issued in behalf of some product or cause or idea or person or institution