Well according to autocar website :
0-60 S3 5.6, TT 5.8
0-100 S3 13.6, TT 15.1
30-70 S3 5.1, TT 5.6
Not much in it, S3 is 1455 KG, 261BHP TT is 1430 KG, 237BHP. I'm also not sure if that was a DSG TT or manual.
S3 probably a bit faster in gears due to more torque over a wider range.
I'd be interested to know how the handling compares, I've not tried a TT 3.2 but I guess they have similar chassis ( aluminium suspension parts ) and 4wd system.