Quick answer
Two interiors again. Scheming produces deceit inside the schemer, while the people working for peace end up with joy.
Read both lines
The verse describes what each occupation does to the person doing it. Deceit is not only what the schemer produces but what fills him, which is the same reflexive logic the book applied to mercy and cruelty at 11:17. Against that, "counselors of peace" is a job description, people whose work is making peace between others, and what they get is joy. Neither half is a reward being handed out. Both are descriptions of what a person becomes by spending their attention one way or the other.
Related: Proverbs 11:17 · Proverbs 12:5 · Matthew 5:9
New King James Version®, Copyright © 1982, Thomas Nelson. All rights reserved. Full copyright information. Scripture provided by API.Bible.
Go Deeper
If this verse has been used to put weight on you that it was never carrying, ask about it directly.