Qualcomm Snapdragon 820 Advantages
Better graphics card performance FLOPS (0.3194 TFLOPS vs 0.1536 TFLOPS )
Larger memory bandwidth (29.8GB/s vs 13.91GB/s)
Higher Frequency (2150MHz vs 1800MHz)
Qualcomm Snapdragon 460 Advantages
More modern manufacturing process (11nm vs 14nm)
Lower TDP (3W vs 11W)
Released 4 years and 2 months late