Intel Xeon E5 4650 's Advantages
Larger L3 cache size (20MB vs 13.75MB)
Lower TDP (130W vs 140W)
Intel Xeon W 2155 's Advantages
Released 5 years and 3 months late
Higher specification of memory (DDR4-2666 vs DDR3)
Higher base frequency (3.3GHz vs 2.7GHz)
More modern manufacturing process (14nm vs 32nm)