Qualcomm Snapdragon 670 Advantages
Better graphics card performance FLOPS (0.3584 TFLOPS vs 0.3244 TFLOPS )
More modern manufacturing process (10nm vs 11nm)
Qualcomm Snapdragon 678 Advantages
Higher Frequency (2200MHz vs 2000MHz)
Lower TDP (6W vs 9W)
Released 2 years and 4 months late