Popatim is correct. Only difference is the hyper threading. 3770k has it, the 3570k doesn't. As far as I know, there are no games that benefit from hyper threading. Mainly applications like Photoshop and CAD see benefits. Along with compressing, decompressing, and video encoding.
I opted to save the money and went with a 3570k with my build and spent the extra money on a better graphics card.
Good luck with whatever you choose!