Group Policy comes in Active Directory. It is a big set of configurations/features etc that can be applied to any computer or user, any program everytime the user logs in to the network, Things like "No allow the user to see the control panel", "Allow only these users to use the comand promtp", "Only allow this user to change the date /time on his computer" etc etc, The number of things that can be controled this way is really huge.
One can also assign applications to a user, and if the apps fails o the remove it from his computer the next time that he logs in the apps is re-installed. If only a library or dll is missing the missing parts get reisntalled, etc etc.
You can also control the way they use the Internet Explorer, I mean it is really big.
I know that we can control the login of the users on the network , the shares (NIS + NFS) we can also have a centrallized database of users (LDAP)
But this other thing , Group Policies, I have not see something like that in any distro. Am I missing something ?