As a logged in user, whether you have access to other users in the system can easily be determined by the presences of the search box that is usually located on the upper left hand side of the interface. This search box will only be visible if you have the ability to see other users. As an admin user type, you will be able to see all users but it is possible based on rights that searching yields a subset of the users. For example, department admins, will only yield users within the department they have rights over.