What is the difference between quattro systems in different Audi models?

I'm considering purchasing an Audi, but I've noticed that different models have different variations of the quattro all-wheel drive system. Can someone explain the differences, and if it affects the overall performance and handling of the vehicle?

The quattro system varies in different Audi models but the basic principle remains the same. In the newer models, an electronic differential lock controls the distribution of power, while in older models, a mechanical differential was used. This may affect the handling and response of the vehicle, especially in challenging road conditions.