NVIDIA GeForce GTX 780M Mac Edition 's Advantages
Boost Clock797MHz
More VRAM (4GB vs 2GB)
Larger VRAM bandwidth (160.0GB/s vs 16.00GB/s)
1216 additional rendering cores
AMD Radeon 520 Mobile 's Advantages
Released 3 years and 5 months late
Lower TDP (50W vs 122W)