Intel Xeon E5649 's Advantages
Higher base frequency (2.533GHz vs 1.3GHz)
Larger L3 cache size (12MB vs 1.5MB)
Intel Xeon D 1577 's Advantages
Released 5 years late
Higher specification of memory (DDR3 vs DDR3)
Newer PCIe version (3 vs 2)
More modern manufacturing process (14nm vs 32nm)
Lower TDP (45W vs 80W)