significance vs message

significance and message both are nouns.

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

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

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

significance (noun)	message (noun)
the quality of being significant	content communicating a message; what something is about
a meaning that is not expressly stated but can be inferred	a communication (usually brief) that is written or spoken or signaled
the message that is intended or expressed or signified