The 560 Ti is faster. That's all you "need" to know. On average, it is 9-12% faster.
The 560 has 336 Shader Units, while the 560 Ti has 384. They are largely identical besides that (same ROPs, nearly the same clock speed, same memory speed and bus width).
In some ways the 560 is closer to the 460 design though. It has the same Shader Units, ROPs, memory bus width, but a MUCH more aggressive clock rate and also faster memory. The 560 is, on average, 13-19% faster than the 460.
Source: techpowerup