User roles in VMM 2012 are used to define the objects and management operations that specified users can create/manage/perform in VMM.
These user roles are as follows:
Administrator: The members of this group can perform tasks/actions on all objects managed by VMM. In addition to this, only administrators can add XenServer hosts and clusters and WSUS servers to VMM.
Fabric (delegated) administrator: The members of this group can perform tasks/actions within their assigned scope (host groups, private clouds, and/or library servers). They can create delegated administrators with a subset of their scope.
Read-only administrator: The members of this group are able to view the status and properties of objects or jobs within their assigned scope (host groups, private clouds, and/or library servers) and specify the Run As accounts that they can view.
Tenant administrator: The members of this group can create/manage self-service users (specifying the tasks/actions they can...