What are the key differences between the Audi A2 and A4 models?

I am trying to decide between purchasing the Audi A2 and A4 models, but I am not sure what sets them apart. Can someone provide some insight into the main differences between these two models?

The main difference between the Audi A2 and A4 models is their size and performance capabilities. The A2 is a compact car with a more economical and efficient engine, while the A4 is a larger sedan with a more powerful engine.