promotional material vs message

promotional material and message both are nouns.

Word	Noun	Adjective	Verb	Adverb
promotional material	Yes	No	No	No
message	Yes	No	Yes	No

As nouns, message is a hypernym of promotional material; that is, message is a word with a broader meaning than promotional material:

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

Other hypernyms of promotional material include content, subject matter, substance.

promotional material (noun)	message (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
	a communication (usually brief) that is written or spoken or signaled