Intel Xeon E5 2603 v3 's Advantages
Higher specification of memory (DDR4-1600 vs DDR3)
Larger L3 cache size (15MB vs 1.5MB)
Intel Xeon D 1521 's Advantages
Released 1 years and 2 months late
Higher base frequency (2.4GHz vs 1.6GHz)
More modern manufacturing process (14nm vs 22nm)
Lower TDP (45W vs 85W)