Intel Xeon D 1521 's Advantages
Released 2 years and 2 months late
Higher specification of memory (4 vs 3)
More modern manufacturing process (14nm vs 22nm)
Lower TDP (45W vs 80W)
Intel Xeon E5 2609 v2 's Advantages
Higher base frequency (2.5GHz vs 2.4GHz)
Larger L3 cache size (10MB vs 1.5MB)