I wrote this for someone else trying to explain that the 460 isn't just an over clocked 560 technically.
There are some differences between the 400 and 500 series cards. FERMI was Nvidia's first run at 40nm fabrication chips. They sort of rushed it out the door, which was evident after the 580 was released with all 512 Cuda cores operational. Pretty much what the 480 should have been when it came out with 480 processor cores.
Nvidia designers tweaked the paths through the GPU to streamline data flows. They also tweaked a few features, increasing overall FP16 texture performance and generally re-designed FERMI architecture to run using slightly less power consumption. In turn less heat dissapation and a better over clockers as end result higher the ceiling a tad.
There are a lot of similarities between the GTX 460 and the GTX 560. Both have the same, 7 SMs, 32 ROPs, 512KB of L2 cache, 1.95B transistor count and 1GB of GDDR5 on a 256-bit memory bus both with 336 processor cores.
The difference? The GTX 460 is on a GF104. The GTX 560 on GF114 and better FERMI design with transistor leakage improvements over GF104 along with the improved data flow architecture.
It's a bit more performance but very slightly. It's not just an over clocked 460 technically.
The GTX 560 runs on par with the AMD 6870.
Next the 560Ti (Titanium). It improves even further and comes with 384 processor cores instead of 336. Has 8 SMs instead of 7 SMs, on a tuned GF114 GPU that finally delivers a full GF104 Fermi architecture and what the GTX 460 should have been. Another difference is transistor-level changes to improve power efficiency and in turn allowed for significantly faster clock speeds.
The GTX 560Ti performs on par with the AMD 6950.
Both are very over clockable. The heavily over clocked 560Ti can even match benches with an unlocked 6950 that's slightly over clocked. The 560Ti due to it's enchancements can handle more of a voltage bump than the GTX 560 allowing higher stable OC's.
So there you have it, some history and the difference between 460, 560 and 560Ti.