Roles are a specialized form of user groups. You can grant permissions to roles or include them in steps within a workflow schema as you can for user groups. However, unlike user groups, the users assigned to roles are not fixed; You can assign users or user groups to a role for individual assets.
Roles are created under the Users folder by a system administrator. Each asset has a roles screen to allow an administrator to assign users or user groups to a role.
You can use roles when you select users or user groups to assign permissions or add them in a workflow schema. In this case, only the users or users groups assigned to that role for that asset will be given that permission or be able to make the approval in Workflow.
Once you have created your roles and assigned them to your site’s assets, you can grant permissions to the roles or use them as conditions within a Workflow Schema. In this case, only the users or user groups assigned that role for that asset can review the content.
Roles are generally not recommended for a system that only has one site. When you use roles, all permission checks within the system can be slower as they are highly dynamic.
If you decide to use roles, make sure you have the hardware to cope with the additional database load. As an alternative, you could try using a dynamic workflow.