Why do some Audi A6 models have more horsepower than others?

I have been researching different Audi A6 models and noticed that some have significantly higher horsepower than others, even within the same model year. What factors determine the horsepower of these vehicles?

The horsepower of Audi A6 models can vary depending on the engine type and trim level. Higher trim levels may have more powerful engines, while certain models may offer an optional upgrade in engine performance. Additionally, newer models tend to have more horsepower due to advancements in technology and engineering.