What are the main differences between the Audi A3 and A4 models?

I am considering purchasing a new Audi and am torn between the A3 and A4 models. Can someone explain the main differences in terms of performance, features, and overall value for money? Thank you in advance!

The main difference between the Audi A3 and A4 models lies in their size and engine options. The A3 is a compact car with a more fuel-efficient four-cylinder engine, while the A4 is a mid-size car with a more powerful six-cylinder engine. In terms of features, the A4 offers more advanced technology such as virtual cockpit and touch-screen infotainment system.