This is probably not the most appropriate comparison to make. Processor generations across such a wide time period such as a decade ago(when the Opteron was commercially available) aren't comparable to todays similar core counterparts. That said, one can compare scores to see the numbers behind what you're paying for:

AMD Opteron : https://browser.geekbench.com/processors/1550 AMD EPYC: https://browser.geekbench.com/processors/2142

Support for faster memory, more PCIe lanes, advanced networking are just some of the differences that the technology family as a whole of current processors offers as a differentiator to processors available in 2011.