Qualcomm Snapdragon 670 Advantages
Better graphics card performance FLOPS (0.3584 TFLOPS vs 0.2176 TFLOPS )
Larger memory bandwidth (14.9GB/s vs 13.9GB/s)
More modern manufacturing process (10nm vs 14nm)
Released 1 years and 3 months late
Qualcomm Snapdragon 660 Advantages
Higher Frequency (2200MHz vs 2000MHz)
Lower TDP (5W vs 9W)