Opteron X2 185 's Advantages
Higher base frequency (2.6GHz vs 2.1GHz)
Lower TDP (110W vs 120W)
AMD EPYC 7251 's Advantages
Released 11 years and 3 months late
Higher specification of memory (DDR4-2400 vs DDR1-400)
More modern manufacturing process (14nm vs 90nm)