Managers have the least access to the back end of Joomla. Managers can create and edit categories and articles. Managers also have access to the media manager and can upload and remove media. Managers are able to work with installed components such as adding banners or weblinks but cannot install or remove extensions.
Administrators have all the rights that Managers have. Administrators additionally have access to User Management, Menu Manager and Extension Manager. Administrators cannot edit Super User accounts or have access to the Global Configuration.
Super Users have full access to the back end. They have all the rights of a Manager and Administrator and additionally have access to the Global Configuration and can add, edit and remove Super Users.