NVIDIA Quadro M4000 's Advantages
More VRAM (8GB vs 4GB)
Larger VRAM bandwidth (192.3GB/s vs 96.13GB/s)
1152 additional rendering cores
NVIDIA Quadro P620 Mobile 's Advantages
Released 2 years and 8 months late
Boost Clock1443MHz
Lower TDP (40W vs 120W)