Intel Xeon E5620 's Advantages
Lower TDP (80W vs 130W)
Intel Xeon E5 2687W v2 's Advantages
Released 3 years and 6 months late
Newer PCIe version (3 vs 2)
Higher base frequency (3.4GHz vs 2.4GHz)
Larger L3 cache size (20MB vs 12MB)
More modern manufacturing process (22nm vs 32nm)