NVIDIA Tesla M40 's Advantages
More VRAM (12GB vs 4GB)
Larger VRAM bandwidth (288.4GB/s vs 96.13GB/s)
2560 additional rendering cores
NVIDIA Quadro P620 Mobile 's Advantages
Released 2 years and 3 months late
Boost Clock has increased by 30% (1443MHz vs 1112MHz)
Lower TDP (40W vs 250W)