Intel Xeon E5 2643 v2 's Advantages
Higher base frequency (3.5GHz vs 3.3GHz)
Larger L3 cache size (15MB vs 13.75MB)
Lower TDP (130W vs 140W)
Intel Xeon W 2155 's Advantages
Released 3 years and 11 months late
Higher specification of memory (DDR4-2666 vs DDR3)
More modern manufacturing process (14nm vs 22nm)