Intel Xeon E5503 's Advantages
Higher base frequency (2GHz vs 1.7GHz)
Larger L3 cache size (4MB vs 1.5MB)
Intel Xeon D 1537 's Advantages
Released 5 years and 8 months late
Higher specification of memory (DDR3 vs DDR3)
Newer PCIe version (3 vs 2)
More modern manufacturing process (14nm vs 45nm)
Lower TDP (35W vs 80W)