There is no difference between the 'Streifenwagen' we don't have something like a "local police", only a state police for each of our states. Some states changed their decals to blue, some didn't. In some states ist green=old cars, blue=new cars, other states stayed totally green. The Federal Police is responsible for railways, airports, the border and the cross-border traffic only, so you don't see their cars very often. They have also changed their decals from green to blue. I hope you understand it, my english is not the best