AMD Radeon R9 M390 Mac Edition 's Advantages
Released 2 years and 1 months late
More VRAM (2GB vs 512GB)
Larger VRAM bandwidth (174.7GB/s vs 80.00GB/s)
640 additional rendering cores
NVIDIA GeForce GTX 660M Mac Edition 's Advantages
Lower TDP (50W vs 80W)