what's the difference between carrera 4s and targa 4s 2012 models

Carrera 4S is offer in coupe and convertible where as the Targa 4S has a oversized sliding glass roof. From wikipedia: In January 2013, Porsche introduced the all-wheel-drive variants of the Carrera models. The '4' and '4S' models are distinguishable by wider tires, marginally wider rear body-work and a red-reflector strip that sits in between the tail-lights. In terms of technology, the new 4 and 4S models are equipped with an all-new all-wheel-drive system that sends power to the front wheels only when there is a need for it, giving the driver a sense of being in a rear-wheel-drive 911 when the conditions are perfect but sending power and torque to the front wheels only when the road and weather conditions are not ideal.