An Open Differential is the basic differential design that allows the two drive wheels to rotate at different speeds, dividing torque equally between them at all times. That equal split is the limitation: because the two sides always receive the same torque, the total the axle can deliver is set by whichever tire has the least grip, so a lifted or slipping inside wheel caps the drive available from both. In a turn it is well behaved and produces no tire scrub, and on a low-power street car its behavior is entirely adequate. For performance use it is the least desirable option under power, which is why limited-slip, torque-sensing and locking designs exist.