What are the most significant differences between the Audi A6 and the A4?

I am trying to decide between the Audi A6 and A4 for my next car. What are the notable differences between these two models in terms of performance, features, and design?

The Audi A6 has a larger and more powerful engine compared to the A4, resulting in a smoother and more responsive driving experience. The A6 also offers more advanced technology features, such as the Virtual Cockpit and a larger infotainment screen.