A program role defines a set of privileges or tasks that a person can perform. Each role includes all the privileges of the roles below it.
Team Agent: The person who completes enrollment is automatically assigned the Team Agent role. This person is also assigned the Legal role in iTunes Connect and is responsible for entering into legal agreements with Apple, including app transfer agreements. There can only be one team agent.
Admin: A person who serves as a secondary contact for teams and has many of the same responsibilities as the team agent. For example, a team admin can assign program roles to others (except for the team agent), manage both development and distribution signing assets, and enable capabilities.
Member: A person who has access to membership benefits, but has limited responsibilities. For example, a team member can create their own development certificate, register a device connected to their Mac, and create a development provisioning profile in Xcode. A team member can’t create distribution certificates and provisioning profiles.
To understand what each role can do, go to Program Roles and iTunes Connect Roles.