Qualcomm Snapdragon 636 Advantages
Lower TDP (5W vs 9W)
Qualcomm Snapdragon 670 Advantages
Better graphics card performance FLOPS (0.3584 TFLOPS vs 0.1843 TFLOPS )
Larger memory bandwidth (14.9GB/s vs 5.3GB/s)
Higher Frequency (2000MHz vs 1800MHz)
More modern manufacturing process (10nm vs 14nm)
Released 10 months late