The major difference for the victims is that in a real kidnapping someone is actually taken from someplace by force and held somewhere else until the ransom is paid. In a virtual kidnapping, loved ones of the victim are the ones who really suffer.
What would happen if a citizen noticed a police officer driving in violation of the law and tried to make a traffic stop? First of all, I would strongly warn against trying something like this, but one guy in the state of Washington did just that and with very surprising results.