Business or domain objects model some essential aspect of the problem domain. Business objects have some correlation with concepts familiar to our software users. Coordinators delegate tasks to others. They are a little less nosy form of controllers. Both are responsible for directing traffic.
Traffic cops take a much more active role.
They know why they are directing traffic and can adjust their behavior accordingly. Controllers are involved in interpreting and reacting to how other objects are working. They exercise more judgment that coordinators. I can't conceive of a traffic light doing so. In fact, old-fashioned traffic lights merely switch from red to yellow to green on preset time intervals, regardless of the traffic.