In RealityHub, the admin is the first & default user created during the installation. After the first installation, the admin can organize the hierarchy inside the user management module. See Installation
The main differences between the admin and other administrators:
The admin can only access User Management and Configuration modules, while administrators can be configured to access all available user features/modules. See the License Reservation
The admin is solely a read-only user. No administrator can remove the admin from the system.
The admin is a member of the read-only “Administration Only” user group and cannot be a member of other user groups, the resolved policies, and cannot have reserved licenses. See Example Module