NVIDIA Tesla M6 's Advantages
More VRAM (8GB vs 2GB)
Larger VRAM bandwidth (160.4GB/s vs 80.13GB/s)
1024 additional rendering cores
NVIDIA Quadro P620 's Advantages
Released 2 years and 6 months late
Boost Clock has increased by 15% (1354MHz vs 1180MHz)
Lower TDP (40W vs 100W)