Intel Xeon D 1521 Advantages
Higher base frequency (2.4GHz vs 2GHz)
More modern manufacturing process (14nm vs 22nm)
Lower TDP (45W vs 105W)
Intel Xeon E5 4620 v3 Advantages
Higher specification of memory (1866 vs 4)
Larger L3 cache size (25MB vs 1.5MB)