^^^yup.
In a Derny race, a rider races a conventional track bike. The Derny pilot is seated, and the Derny has both an engine and a pedal drive - which lets the pilot make small, steady adjustments to the speed.
In a steher race, steher pilots are standing to throw a huge draft. They are piloting big motorcycles with a roller on the rear, and the racer has a special bike with a small front wheel and a huge amount of trail. Never ridden one but I can't imagine they handle very fast!
