There are two sections, one to maintain Contacts, the other is to maintain Service Agents.
Contacts: The contacts are the vendor contacts which is the main source of contact you will have with the vendor as a whole. Most of the time, they can view all Service Orders that are sent to that Vendor
Service Agents: The service agents are those who are working directly with you on the particular project.
For example, let’s use a Real Estate Vendor. The Contact could be a manager in charge of a group of real estate agents. The Agents would then be the real estate agents in which would be providing the services.
Thus, you may start your conversation with the vendor at the Contact level, but then move to the Service Agent level in regards to more specific projects. One important thing to note is that Contacts will be able to see the entire system, whereas Service Agents are limited to their own specific assignments.
Note: You can mark a Contact or Service Agent Inactive. By marking the Contact or Service Agent Inactive, they will not appear in the drop down list when you go to select your Vendor Contacts for a new Service Order nor will the Inactive Contact or Service Agent be available for selection in the To/CC/BCC when creating a new email communication
Vendors may have a Program Manager that is the "Vendor Contact" that receives the Service Orders and then assigns the Service Order to an "Service Agent"
To be able to associate Service Agents with the Service Orders, Go to Service Order Settings screens and make sure that the Service Agent Field Setting is enabled to Show Agent. Learn more on how to manage service order settings.