Intel Xeon E5 4640 's Advantages
Higher base frequency (2.4GHz vs 1.5GHz)
Larger L3 cache size (20MB vs 1.5MB)
Intel Xeon D 1557 's Advantages
Released 3 years and 9 months late
Higher specification of memory (4 vs 3)
More modern manufacturing process (14nm vs 32nm)
Lower TDP (45W vs 95W)