What are the differences between Audi's Quattro versus Quattro Ultra system?

I have heard of Audi's Quattro system, but recently came across the Quattro Ultra system. What are the main differences between these two systems and how do they affect overall performance and driving experience?

Audi's Quattro system is a permanent all-wheel drive system, featuring a 40:60 rear-biased power distribution for optimal handling. Quattro Ultra, on the other hand, is a new generation of intelligent four-wheel drive that can switch between front-wheel drive and all-wheel drive depending on driving conditions and demand. This helps improve fuel efficiency while still maintaining a high level of grip and traction.