Qualcomm Snapdragon 820 Advantages
Larger memory bandwidth (29.8GB/s vs 17GB/s)
Qualcomm Snapdragon 750G Advantages
Better graphics card performance FLOPS (0.4224 TFLOPS vs 0.3194 TFLOPS )
Higher Frequency (2200MHz vs 2150MHz)
More modern manufacturing process (8nm vs 14nm)
Lower TDP (5W vs 11W)
Released 4 years and 10 months late