What is the difference between Audi A4 S line and S4?

I'm looking to purchase a new Audi A4, but I'm unsure of the differences between the S line and S4 models. Can someone please provide an explanation?

The main difference between the Audi A4 S line and S4 is the performance. The S line model features a more powerful engine and enhanced suspension for better handling, while the S4 is a full performance model with even more power and sportier features.

In terms of appearance, the S line and S4 models both have sportier features such as a unique front grille and larger wheels. However, the S4 also includes quad exhaust pipes and a more aggressive body design.