What is the difference between Audi A6's TFSI and TDI engines?

I was researching the Audi A6 and noticed that it has both TFSI and TDI engines. Can someone explain the difference between the two and which one is better?

The main difference between TFSI and TDI engines lies in their combustion process. TFSI engines use a turbocharger to compress air and fuel mixture before ignition, resulting in better fuel efficiency and lower emissions. TDI engines use a diesel fuel injection system to ignite the fuel, providing more torque and overall power.

In my opinion, TFSI engines are better suited for daily city driving, while TDI engines are better for long-distance highway driving. TDI engines have a higher fuel efficiency on the open road, but TFSI engines are more responsive and agile in city traffic.

Personally, I prefer TFSI engines for their smoother and quieter performance. TDI engines can be noisier at low speeds due to their diesel injection process. TFSI engines also have a wider availability of fuel options, as most gas stations offer regular and premium gasoline.