Intel Xeon E5 2660 's Advantages
Higher base frequency (2.2GHz vs 1.9GHz)
Larger L3 cache size (20MB vs 8MB)
Intel Xeon E3 1558L v5 's Advantages
Released 4 years and 2 months late
Higher specification of memory (2133 vs 3)
More modern manufacturing process (14nm vs 32nm)
Lower TDP (45W vs 95W)