Xeon E7 2820 's Advantages
Higher specification of memory (1333 vs 3)
Lower TDP (105W vs 115W)
Intel Xeon E5 2670 v2 's Advantages
Released 2 years and 5 months late
Higher base frequency (2.5GHz vs 2GHz)
Larger L3 cache size (25MB vs 18MB)
More modern manufacturing process (22nm vs 32nm)