Intel Xeon W3690 's Advantages
Higher base frequency (3.466GHz vs 3.2GHz)
Larger L3 cache size (12MB vs 8.25MB)
Intel Xeon W 2104 's Advantages
Released 6 years and 6 months late
Higher specification of memory (DDR4-2666 vs DDR3)
Newer PCIe version (3 vs 2)
More modern manufacturing process (14nm vs 32nm)
Lower TDP (120W vs 130W)