Intel Xeon E3 1275 v2 's Advantages
Higher base frequency (3.5GHz vs 2.6GHz)
Lower TDP (77W vs 135W)
Intel Xeon E5 1686 v3 's Advantages
Released 2 years and 4 months late
Higher specification of memory (DDR4-2133 vs DDR3)
Larger L3 cache size (30MB vs 8MB)