The difference between a constant velocity joint and a Universal joint is in the theory of operation. A single constant velocity joint transmits the same speed from input to output regardless of the misalignment. A single universal joint with a constant input speed will have changing output speed due to angular velocity changes inherent to a universal joint. When a second joint is put in phase with the first joint, the velocity change is countered from joint to joint so the input speed at the first joint will be the same as the output speed after the second joint. Constant velocity joints are usually much larger than the equivalent universal joint and are generally used in the automotive industry, not in industrial applications.