Can someone describe me the difference between Automatic Transmission (AT) and FAT?

How odd to see that term these days. It stands for "fully automatic transmission," which was a meaningful differentiation about 50 or 60 years ago from an automatic clutch transmission that you still had to shift (much like in motorcycles and certain race cars). Perhaps they are bringing the term back because of the emergence of sports shift automatics, that allow you to act like you are driving a manual (even though you aren't). The Fit is one of the cars that have "shift paddles," but I think they are only available on Sport models that have old-fashioned slush box automatic transmissions, not the new CVTs. But don't quote me on that, I am guessing.