Powertrain is the same. However, power mapping changes for more instant throttle response when in Sport mode and steering assist tightens. You also get the use of all 650 volts of the battery (and hence torque) from the start vs 500 volts in Eco or Normal. However, overall available power if you floor the pedal in Eco and Normal modes kick in to 650 volts regardless due to safety (emergency passing for instance).
Over two years of ownership and it's been a fantastic sporty and fun to drive car with the bonus of excellent fuel economy of 48 mpgs (5 L/100km)! If you don't mind the firmer ride and smaller interior, get in a CT, you won't regret it!