promo vs subject matter

promo and subject matter both are nouns.

Word	Noun	Adjective	Verb	Adverb
promo	Yes	No	No	No
subject matter	Yes	No	No	No

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

promo: a message issued in behalf of some product or cause or idea or person or institution
subject matter: content communicating a message; what something is about

Other hypernyms of promo include content, message, substance.

promo (noun)	subject matter (noun)
a message issued in behalf of some product or cause or idea or person or institution	content communicating a message; what something is about