ballyhoo vs promo

ballyhoo and promo both are nouns.

Word	Noun	Adjective	Verb	Adverb
ballyhoo	Yes	No	Yes	No
promo	Yes	No	No	No

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

ballyhoo: blatant or sensational promotion
promo: a message issued in behalf of some product or cause or idea or person or institution

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

ballyhoo (noun)	promo (noun)
blatant or sensational promotion	a message issued in behalf of some product or cause or idea or person or institution

ballyhoo (verb)	promo (verb)
advertize noisily or blatantly