they are identical in power ratings. They both have identical chassis and drivetrain.
For some reason though, I remember reading in Car and Driver a few years back when the 30th anniv. T/A came out that the Trans Am topped out at 163 governed and the SS was drag limited to 159 or so.
But when they stomp on the gas and you see all the blow-by black smoke puff out of the exhaust...the smoke does that swirling, tornado-like trick and it does look pretty cool