What's the difference between Adaptive Cruise Control (ACC) and Traffic Jam Assist (TJA) in Audi A8?

I've heard that the Audi A8 offers both Adaptive Cruise Control (ACC) and Traffic Jam Assist (TJA) as optional features. What are the main differences between these two systems and how do they work?

Adaptive Cruise Control (ACC) automatically maintains a safe following distance from the vehicle ahead by adjusting the speed of your car. On the other hand, Traffic Jam Assist (TJA) takes this a step further by also steering the car for you in heavy traffic, making your commute more relaxed.

ACC is best used on highways or open roads, where there is a clear path ahead. TJA is more useful in heavy traffic situations, where frequent stopping and starting can be tiring and stressful for the driver.