Riot troopers were a type of troopers in the Imperial Army. They had metal batons and riot shields, but their armor was the same as stormtrooper armor. It also had red markings on it. Their batons had tazers on the ends. Not much is known about these troops.
In the Clone Wars, there was a type of clone trooper that had the same job as riot troopers.
These were eventually replaced by Imperial riot troopers.