Qualcomm Snapdragon 821 Advantages
Better graphics card performance FLOPS (0.3343 TFLOPS vs 0.1552 TFLOPS )
Larger memory bandwidth (29.8GB/s vs 13.91GB/s)
Higher Frequency (2342MHz vs 2200MHz)
MediaTek Helio P90 Advantages
More modern manufacturing process (12nm vs 14nm)
Lower TDP (5W vs 11W)
Released 2 years and 3 months late