Qualcomm Snapdragon 626 Advantages
Higher Frequency (2200MHz vs 2000MHz)
Qualcomm Snapdragon 662 Advantages
Better graphics card performance FLOPS (0.2432 TFLOPS vs 0.1248 TFLOPS )
Larger memory bandwidth (13.9GB/s vs 7.5GB/s)
More modern manufacturing process (11nm vs 14nm)
Lower TDP (4W vs 11W)
Released 3 years and 3 months late