the key element that differentiates a terry stop from an arrest is
Terry stop In the United States, a Terry stop is a brief detention of a person by police on reasonable suspicion of involvement in criminal activity but short of probable cause to arrest.[1]
School bus traffic stop laws Generally, if a stopped school bus is displaying a flashing, alternating red lamp, a driver of a vehicle meeting or overtaking the stopped bus from either direction (front or back) must stop and wait until the bus moves again or the red light is off.[1] Police officers, school crossing guards, and even school bus drivers themselves may have the power to wave traffic on, even when a red light is flashing.