I think the 600D is more of a comparison for the Nikon 5100. The Nikon has a faster focus speed in real world scenarios. Canon has an advantage as the lenses are cheaper. A 50mm f1.8 with autofocus(which is considered as the best entry point lens) is a lot cheaper for canon than nikon. The nikon model with manual focus is cheap, but the one with autofocus is almost the price of as the canon 50mm f1.4 USM model.
Canon RAW files are larger in size, thus the buffer fills up quicker when your doing continuous shooting. Nikon would be better for action/sports photography.