Not much info regarding these two cards except for speculations that the 470 will most likely be a cut-down Polaris 10 with a 110w tdp. Lisa Su did indicate the 460 will have a <75w tdp so most likely 460 is Polaris 11. Current card that matches Polaris 11 in terms of specs is the R7-370 which also has 16 CUs and 2tflops of processing power. With higher clocks not to mention optimization on the archi itself, the RX 460 can be right around GTX 960/R9-380 performance.
Edit:
New leaked performance slides just came out
that puts the RX 470 right around R9-290 performance. IT seems TDP will most likely be 110w as well. The RX480M in the slide I believe is the full Polaris 11. But since it's been known at least for AMD based gpus, that laptops based gpus are underclocked to fit in to the laptops tdp limit, so the RX 480M could be slower than it's desktop equivalent, the RX 460.