Qualcomm Snapdragon 820 Advantages
Larger memory bandwidth (29.8GB/s vs 25.6GB/s)
Qualcomm Snapdragon 778G Plus Advantages
Better graphics card performance FLOPS (0.8448 TFLOPS vs 0.3194 TFLOPS )
Higher Frequency (2500MHz vs 2150MHz)
More modern manufacturing process (6nm vs 14nm)
Lower TDP (5W vs 11W)
Released 5 years and 11 months late