Qualcomm Snapdragon 680 Advantages
More modern manufacturing process (6nm vs 10nm)
Released 4 years and 11 months late
Qualcomm Snapdragon 835 Advantages
Better graphics card performance FLOPS (0.5675 TFLOPS vs 0.284 TFLOPS )
Larger memory bandwidth (29.8GB/s vs 17GB/s)
Higher Frequency (2450MHz vs 2400MHz)