It is imperative to understand the technology of DSLR cameras before contrasting the differences between to models.
Compare digital SLR cameras of Canon and Nikon
These are not just simple 'point and shoot' units. The DSLR, short for Digital Single Lens reflex gives users the ability to make the picture turn out the exact same as what is seen through the eye lens, or viewfinder.
In the 'point and shoot' units, the scene depicted in the viewfinder is not the same as what come through the primary lens. The viewfinder portion is not indicate of final product in traditional digital cameras. Therefore, in the DSLR cameras, the images are the same. Therefore, the photo taker will be able to take a picture that will turn out the same as what is seen through the viewfinder. This visualization makes picture taking much easier and more accurate.
There are three basic categories for both Canon and Nikon for SLR digital categories. Beginning with the amateur level machines, the Canon Rebel XS (1000D) and also the Nikon D60 fall into that category. There are many differences between the Rebel XS and Nikon D60. If you have older Canon lenses you want to use with it, the Nikon D60 will work with most of them; while the older Nikon lenses may not work with the Nikon D60.
The next category of these cameras is for more professional use. These are usually larger and more expensive. They require some expertise to use effectively. Cameras that fall into this category are the Canon Rebel T1i 500D as well as the Nikon D 5000. The Canon Rebel T1i and the D5000 are actually very similar in their capabilities; although the ISO range varies. The D5000 range is 100-6400 while the T1i has a larger range of 100-12800.
Finally, there is another category to compare digital SLR cameras. They fuse together several of the features from each of the previous categories. These can be used by amateur photographers who want to take more professional quality pictures. In this category, the Nikon D300 and Canon 50D would meet those needs. These are both really good cameras and are almost identical in their features. There are a few subtle differences; the Canon is actually lighter at 29 oz than the Nikon at 32.6 oz. Also, the ISO range is slightly different; the Canon ISO boasts 100-12800 where the Nikon range is 100-6400.