What is the difference between Audi A8 quattro and Audi A8 4.0T quattro?

I am looking into buying an Audi A8 and noticed these two variations. Is one better than the other? What does the 'T' stand for in 4.0T?

The main difference between Audi A8 quattro and Audi A8 4.0T quattro is the engine. The 4.0T model has a turbocharged engine, whereas the standard quattro has a non-turbocharged engine. The 'T' in 4.0T stands for 'turbo'. In terms of performance, the 4.0T may have slightly quicker acceleration and a bit more torque, but ultimately, it depends on your personal preferences and needs.