Qualcomm Snapdragon 821 Advantages
Better graphics card performance FLOPS (0.3343 TFLOPS vs 0.2496 TFLOPS )
Larger memory bandwidth (29.8GB/s vs 14.9GB/s)
Higher Frequency (2342MHz vs 1850MHz)
Released 11 months late
Apple A9 Advantages
Lower TDP (5W vs 11W)