sales promotion vs promo

sales promotion and promo both are nouns.

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

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

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

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

sales promotion (noun)	promo (noun)
promotion that supplements or coordinates advertising	a message issued in behalf of some product or cause or idea or person or institution