Intel Xeon E5 2403 's Advantages
Lower TDP (80W vs 105W)
Intel Xeon E5 2660 v3 's Advantages
Released 2 years and 4 months late
Higher specification of memory (DDR4-2133 vs DDR3)
Higher base frequency (2.6GHz vs 1.8GHz)
Larger L3 cache size (25MB vs 10MB)
More modern manufacturing process (22nm vs 32nm)