Intel Xeon D 1521 's Advantages
Higher base frequency (2.4GHz vs 2.1GHz)
Lower TDP (45W vs 120W)
Intel Xeon w3 2423 's Advantages
Released 7 years and 3 months late
Higher specification of memory (4400 vs 4)
Newer PCIe version (5 vs 3)
Larger L3 cache size (15MB vs 1.5MB)
More modern manufacturing process (10nm vs 14nm)