The Nikon D5000 sensor obtains exceptional results for low ISO settings and outperforms the Canon EOS 500D sensor in dynamic range and color depth. When ISO increases, however, the differences become smaller, but the Nikon D5000 still maintains a slight advantage.
This said, the Canon EOS 500D sensor is nevertheless an exceptional sensor with a very small pixel pitch and very low RAW noise. Two main weaknesses explain the difference between its score and that of the Nikon:
We should keep in mind, too, that the sensor launched by Canon presents more technical challenges than a classic 5.5µm pixel pitch sensor, and in principle should provide slightly higher resolution. Of course, this DxOMark review evaluates only RAW sensor performance and should be considered only in tandem with other more global reviews when choosing a digital camera. While DxOMark does take resolution into account for normalization, users should be aware about the minimum resolution they need before comparing any camera.