Qualcomm Snapdragon 821 Advantages
Better graphics card performance FLOPS (0.3343 TFLOPS vs 0.0432 TFLOPS )
Higher Frequency (2342MHz vs 1400MHz)
More modern manufacturing process (14nm vs 28nm)
Released 11 months late
Qualcomm Snapdragon 430 Advantages
Lower TDP (6W vs 11W)