NVIDIA GeForce GTX 680M 's Advantages
More VRAM (4GB vs 2GB)
Larger VRAM bandwidth (115.2GB/s vs 14.40GB/s)
1088 additional rendering cores
NVIDIA GeForce 920MX 's Advantages
Released 3 years and 9 months late
Boost Clock has increased by 31% (993MHz vs 758MHz)
Lower TDP (16W vs 100W)