NVIDIA GeForce GTX 680M 's Advantages
More VRAM (4GB vs 2GB)
Larger VRAM bandwidth (115.2GB/s vs 88.00GB/s)
576 additional rendering cores
AMD Radeon R9 M270X 's Advantages
Released 2 years and 8 months late
Boost Clock has increased by 32% (1000MHz vs 758MHz)