Intel Xeon E5 1691 v3 's Advantages
Higher base frequency (2.5GHz vs 1.9GHz)
Larger L3 cache size (35MB vs 8MB)
Intel Xeon E3 1558L v5 's Advantages
Released 1 years and 8 months late
Higher specification of memory (2133 vs 2133)
More modern manufacturing process (14nm vs 22nm)
Lower TDP (45W vs 135W)