Intel Xeon D 1521 's Advantages
Released 3 years and 8 months late
More modern manufacturing process (14nm vs 32nm)
Lower TDP (45W vs 115W)
Intel Xeon E5 2689 's Advantages
Higher specification of memory (1600 vs 4)
Higher base frequency (2.6GHz vs 2.4GHz)
Larger L3 cache size (20MB vs 1.5MB)