Intel Xeon E5 2640 's Advantages
Higher base frequency (2.5GHz vs 1.7GHz)
Lower TDP (95W vs 105W)
Intel Xeon E5 4648 v3 's Advantages
Released 3 years and 3 months late
Higher specification of memory (1866 vs 3)
Larger L3 cache size (30MB vs 15MB)
More modern manufacturing process (22nm vs 32nm)