Intel Xeon E5 2666 v3 's Advantages
Larger L3 cache size (25MB vs 22.5MB)
Lower TDP (135W vs 150W)
Intel Xeon Gold 5415 's Advantages
Released 8 years and 2 months late
Higher specification of memory (DDR5-4400 vs DDR4-2133)
Newer PCIe version (5 vs 3)
More modern manufacturing process (10nm vs 22nm)