Intel Xeon E5 2666 v3 's Advantages
Higher specification of memory (DDR4-2133 vs DDR4-1866)
Higher base frequency (2.9GHz vs 1.7GHz)
Intel Xeon E5 4648 v3 's Advantages
Released 7 months late
Larger L3 cache size (30MB vs 25MB)
Lower TDP (105W vs 135W)