topic vs message

topic and message both are nouns.

Word	Noun	Adjective	Verb	Adverb
topic	Yes	No	No	No
message	Yes	No	Yes	No

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

Other hypernyms of topic include content, subject matter, substance.

topic (noun)	message (noun)
some situation or event that is thought about	content communicating a message; what something is about
the subject matter of a conversation or discussion	a communication (usually brief) that is written or spoken or signaled