Both have the same bandwidth: 80GB/s, as they use the same memory. Polaris has much more efficient color compression, which means it can utilise the bandwidth better. The stock 965M has max theoretical 1.94 GFLOPS while the 460 Pro has 1.86 GFLOPS. Both numbers are of course theoretical peaks and therefore less indicative of real-world performance. Both GPUs are fairly good at utilising their resources in heterogeneous scenarios, but Polaris might have a slight edge here. I think it might be fairly close.