Intel Xeon E5 2666 v3 's Advantages
Higher base frequency (2.9GHz vs 2.7GHz)
Lower TDP (135W vs 350W)
Intel Xeon Platinum 8558P 's Advantages
Released 9 years and 1 months late
Higher specification of memory (DDR5-4800 vs DDR4-2133)
Newer PCIe version (5 vs 3)
Larger L3 cache size (260MB vs 25MB)
More modern manufacturing process (7nm vs 22nm)