Qualcomm Snapdragon 665 Advantages
Lower TDP (5W vs 6W)
Qualcomm Snapdragon 870 Advantages
Better graphics card performance FLOPS (1.3721 TFLOPS vs 0.2432 TFLOPS )
Larger memory bandwidth (44GB/s vs 14.9GB/s)
Higher Frequency (3200MHz vs 2000MHz)
More modern manufacturing process (7nm vs 11nm)
Released 1 years and 9 months late