The GeForce GTX 560 has clock speeds of 810 MHz on the GPU, and 1001 MHz on the 1024 MB of GDDR5 memory. It features 336 SPUs as well as 56 TAUs and 32 Rasterization Operator Units.
Compare those specs to the GeForce GTX 560 Ti, which comes with a clock frequency of 822 MHz and a GDDR5 memory speed of 1002 MHz. It also uses a 256-bit bus, and makes use of a 40 nm design. It is made up of 384 SPUs, 64 TAUs, and 32 ROPs.
In short ; 560 ti is faster.