AMD Radeon R9 M290X 's Advantages
More VRAM (4GB vs 2GB)
Larger VRAM bandwidth (153.6GB/s vs 14.40GB/s)
896 additional rendering cores
AMD Radeon 620 Mobile 's Advantages
Released 5 years and 4 months late
Boost Clock has increased by 14% (1024MHz vs 900MHz)
Lower TDP (50W vs 100W)