If setup.exe is run from the distribution kit directory of the version that is already installed on the user computer, the installed version will be updated automatically in compliance with the settings specified in the InstallComponents parameter of the configuration files (see page 241).
If setup.exe is run from the distribution kit directory of the version that is not installed on the computer yet, this version will be installed instead of updating any of the previously installed versions.
To enable Microsoft Windows users that do not possess administrator rights in the operating system to update 1C:Enterprise installed by an administrator, you need to set the AlwaysInstallElevated policy for the computer and the user. The policy can be set both locally in the Group Policies control panel (by running gpedit.msc) or using Active Directory policy management.
The above actions are available for the Authenticated users group and not for some specific users.