The System Policy Editor is a tool that comes with NT 4.0 and allows you to make conditional changes to the registry. For example you can set up a policy so students can not make changes to the registry. Other policies could be to remove the control panel.
Policies come in three forms user, group or computer.
There is a default user and also a default computer policy. These policies apply to all users and all computer respectively. You can modify these default policies using the policy editor. You can also create a new user policy that will over ride the default user policy. The user policy is associated with a user by setting the name of the user policy to the name of the user.