1.8t vs. 1.8t ultra sport

besides the cosmetics of the car, i know the ultra sport version comes
with more hp than a regular 1.8t. But is it faster because of how it's
electronically tuned, or is there a mechanical difference. And if i was
to chip a regular A4 would the hp output be the same as if i were to
chip an ultra sport, or would it be a lil less. I'm curious cuz i'm
looking into getting a b6 but i just wanna get some facts straight. I've
heard mixed facts and opinions from everyone one, so i'm a lil unsure.