Xeon E5335 's Advantages
Lower TDP (80W vs 135W)
Intel Xeon E5 1691 v3 's Advantages
Released 7 years and 10 months late
Higher specification of memory (DDR4-2133 vs DDR3
Depends on motherboard)
Higher base frequency (2.5GHz vs 2GHz)
More modern manufacturing process (22nm vs 65nm)