A Comparison of specifications can be found at;
Official specifications of Canon T3i/600D can be found at;
Official specifications of Nikon D5100 can be found at;
However, it should be noted that Nikon D5100 boasts better low light performance owing to its higher ISO sensitivity. Whereas, some dSLR videographers prefer Canon T3i/600D over Nikon D5100 due to better manual control capabilities found on the former camera.