Intel Xeon E5 2640 v3 's Advantages
Larger L3 cache size (20MB vs 13.75MB)
Lower TDP (90W vs 140W)
Intel Xeon W 2155 's Advantages
Released 2 years and 11 months late
Higher specification of memory (DDR4-2666 vs DDR4-1866)
Higher base frequency (3.3GHz vs 2.6GHz)
More modern manufacturing process (14nm vs 22nm)