How can a school policy be managed

You need to be more specific. A school can manage policies like dress codes for example but policies can be written that are unmanageable. If a school has a policy that students must spend two hours each night on homework, that is unmanageable.

Management and control are about the same thing. You can only manage things within your ability to control. You can call the parent and have them take the child home to change clothes but you can't send someone with a stop-watch home with every child to time how long they work on their schoolwork.