Intel Xeon E5645 's Advantages
Higher base frequency (2.4GHz vs 1.8GHz)
Larger L3 cache size (12MB vs 1.5MB)
Intel Xeon D 1581 's Advantages
Released 5 years and 11 months late
Higher specification of memory (4 vs 3)
Newer PCIe version (3 vs 2)
More modern manufacturing process (14nm vs 32nm)
Lower TDP (65W vs 80W)