A Trimble timing device is a receiver that calculates the time of transmission and reception of a signal to compute the distance between itself and an object or another receiver. The timing receivers support different radio signals, which provide varying levels of accuracy at different price points. The radio systems choose the most accurate signals available depending upon environment, availability, cost-effectiveness, etc.
Meanwhile, a positioning device is a receiver that calculates its location on Earth by transmitting signals to and receiving them from satellites in orbit around Earth. It uses those calculations to determine its location anywhere on Earth.