What is the difference between the Audi A8 55 and A8 60?

I have been considering purchasing a new Audi A8, but I am confused about the different model options. Can someone explain the differences between the A8 55 and A8 60?

The main difference between the Audi A8 55 and A8 60 is the engine size and power. The A8 55 has a 3.0-liter V6 engine with 335 horsepower, while the A8 60 has a 4.0-liter V8 engine with 453 horsepower.

Another difference is the fuel economy. The A8 55 gets an estimated 23 mpg combined, while the A8 60 gets 20 mpg combined. This may not seem like a big difference, but it can make a significant impact over time.