You can easily get this by
a) Check what Full Frame means (sensor size) and what other formats are there.
b) Check www.canon.com for details of the camera.
c) Check review pages and find the specs of the sensor
Btw: Cameras are not cars where you can the same model with 1.6l engine or 2.5l - the whole camera is built around one sensor size. 50D or 5D - they only come in one sensor size.
If you want to get a camera with exchangeable sensor .. well, be prepared to pay a few dollars more and have a look here.