What are the differences between Audi's Quattro and Quattro with ultra technology?

I've heard about Audi's Quattro technology, but I'm not sure what sets it apart from the Quattro with ultra technology. Can someone explain the differences between these two?

Quattro technology is Audi's innovative all-wheel drive system, originally developed for rally racing. It continuously monitors road conditions and distributes power to the wheels with the most traction. Quattro with ultra technology is a newer version, designed for fuel efficiency. It automatically disengages the rear wheels when not needed, resulting in improved fuel economy without sacrificing performance.

Quattro and Quattro with ultra technology both provide superior traction and handling in various road conditions. However, Quattro with ultra technology is specifically designed for front-wheel drive-based platforms, while Quattro can be used on both front and rear-wheel drive vehicles. Ultimately, both technologies offer impressive performance and stability.

As the name suggests, Quattro with ultra technology is a more eco-friendly version of the original Quattro. By disengaging the rear wheels when not needed, it reduces drag and improves fuel efficiency by up to 17%. However, if you value maximum traction and performance over fuel economy, the standard Quattro may be the better option.