Messaging is just that - words telling others something... about you, your organization, your service or business or your delicious donuts.
Signaling is about the emotional experience of how you say what you say and what they feel when your message reaches them.
A big, expensive engagement ring is a signal.
An expensive venue or priority postage is a signal.
Messaging is your editorial and brand guides. Those are easy. Those are inexpensive, but they'll cost you in the end.
If messaging confuses cost with value you'll go broke saving money.