There are two different sizes of DSLR: Crop-frame and full-frame. While the sensor size in crop-frame versions vary from brand to brand, they are typically 1.5x smaller than their full-frame counterparts. The sensor in a full-frame camera is the same size as a photo produced on 35mm film. But what’s the advantage to having a bigger sensor?
This article from Photography Talk looks at some of the advantages of a Full Frame camera.