Intel Xeon E3 1235 's Advantages
Higher base frequency (3.2GHz vs 1.8GHz)
Larger L3 cache size (8MB vs 1.5MB)
Intel Xeon D 1581 's Advantages
Released 4 years and 10 months late
Higher specification of memory (4 vs 3)
More modern manufacturing process (14nm vs 32nm)
Lower TDP (65W vs 95W)