Admin user can enable or disable displayed modules. Operator user can only view modules that are enabled by the admin user. If the module is disabled, it will no longer be visible to any of the users. This holds good for Add-On modules as well.
To enable/disable module click on Settings → Basic settings → System Settings → General tab, and select the modules that you would like to be displayed from 'Displayed modules' and click on Save. The enable/disable changes will be applied immediately.