Why do some Audi A3 models have a diesel engine while others have a petrol engine?

I noticed that while researching the Audi A3, some models have a diesel engine while others have a petrol engine. What is the reason for this difference and how does it affect the performance and fuel efficiency of the car?

The difference in engines for the Audi A3 can be attributed to the different models and their intended use. The diesel engine is more suited for long distance driving and offers better fuel efficiency, while the petrol engine is better for short distance driving and provides a smoother and more responsive driving experience.