Can someone explain what the difference is between the long wheel base and the short/regular wheel base? How do you tell the difference?

Look at the rear door it looks shorter. The car is 120 cm shorter from the middle pillar to the rear bumper. electric rear seats, parktronic, and electric rear blind are all optional extras with the short wheelbase model.

Normally the longer wheelbase make more stability during braking than the short wheelbase. B'cos due to the weight distribution between the front & rear of vehicle when heavy brake are applied is much more reduced with longer wheelbase.