Qualcomm Snapdragon 810 Advantages
Better graphics card performance FLOPS (0.3072 TFLOPS vs 0.2176 TFLOPS )
Larger memory bandwidth (25.6GB/s vs 13.9GB/s)
Qualcomm Snapdragon 660 Advantages
Higher Frequency (2200MHz vs 2000MHz)
More modern manufacturing process (14nm vs 20nm)
Released 3 years and 1 months late