There are two main differences between BUF503X and Torq 10FX. The overall shape of both polishers differs from each other. BUF503X is 680 watts, while on the other hand, Torq 10FX is 700 watts. So if you are purchasing a polisher for personal use, Torq 10FX would be the best option. If you purchase a polisher for business, you must buy Torq 10FX.