NVIDIA GeForce GT 640M Mac Edition 's Advantages
Lower TDP (32W vs 250W)
AMD Radeon R9 M395 Mac Edition 's Advantages
Released 2 years and 3 months late
More VRAM (2GB vs 512GB)
Larger VRAM bandwidth (174.7GB/s vs 40.00GB/s)
1408 additional rendering cores