Intel Xeon E5 2420 's Advantages
Larger L3 cache size (15MB vs 8.25MB)
Lower TDP (95W vs 140W)
Intel Xeon W 2135 's Advantages
Released 5 years and 3 months late
Higher specification of memory (2666 vs 3)
Higher base frequency (3.7GHz vs 1.9GHz)
More modern manufacturing process (14nm vs 32nm)