Quadro K1200 Advantages
More VRAM (4GB vs 2GB)
Larger VRAM bandwidth (80.00GB/s vs 48.06GB/s)
128 additional rendering cores
Quadro P520 Mobile Advantages
Released 4 years and 4 months late
Boost Clock has increased by 33% (1493MHz vs 1124MHz)
Lower TDP (18W vs 45W)