Alfredo Cornejo :
what's the difference between these cards and is it worth it to get 770 instead
More CUDA Cores, higher stock clocks, and a larger memory bandwidth. Is it worth it? IMO it is...but it would be best to read some benchmarks on both cards and decide for yourself.
GTX 760: http://www.nvidia.com/gtx-700-graphics-cards/gtx-760/
GTX 770: http://www.nvidia.com/gtx-700-graphics-cards/gtx-770/
Again, my vote is for the GTX 770.