How does Audi R8's Quattro all-wheel drive system work?

I am curious about the technology behind the Quattro all-wheel drive system in the Audi R8. Can you explain it in detail and how it differs from other all-wheel drive systems?

The Quattro all-wheel drive system is unique to Audi and operates on a mechanical, self-locking center differential which distributes torque between the front and rear axles. It can send up to 85% of the power to the rear wheels or up to 70% to the front wheels as needed for optimal traction.