[vectorit]

Yes, an open differential allows different speeds through a turn.

Again:

When a driver shifts from two- to four-wheel drive in a vehicle with part-time four-wheel drive, he or she locks together the front and rear axles, so the front and rear wheels rotate at the same speed. This improves straight-line traction.

Since the part-time system has no center differential, there is no way for the two axles to rotate at different speeds in a corner. So, part-time systems shouldn't be engaged unless the vehicle is on very slippery road conditions such as deep snow and mud where wheels can slip as necessary for turning.

If you try driving one of these vehicles on dry pavement with four-wheel drive activated, you will likely feel an awkward, binding sense as you turn a corner. It's also possible to damage drive system components on these vehicles and cause premature tire wear if you travel in four-wheel drive on dry pavement.