See it all the time, but not totally sure what it means?
Deal
Prior to the actual signing of the contract the work is considered a deal. From a Parallax perspective, deals are brought in from the CRM tool and reflect what is intended on being sold.
Deals can be found in the Sales Pipeline.
Project
A project follows the CRM win condition to represent the work sold in preparation for delivery.
Projects can be found in the Active Projects amongst other places. As a starting point, please see the Project Detail Article.