Tom Warren : Xbox Series X VS Xbox Series S specs

The Xbox One X came out a couple years after the One S. They took the One S CPU and tweaked it a bit and ran it at a higher clock frequency, so got some additional performance. It wasn't a huge departure thiugh, it was only slightly stronger and is essentially the same design with a couple optimizations. They were able to do that as they had several additional years to analyze how games were using the One and One S CPUs.

But this time the console versions are releasing at the same time so it makes sense to just use the same CPU. They can't really reduce the core count, since that would effect how games need to be coded more thoroughly. They could probably underclock it a bit to save some power, but there's not really another change they could easily make.

/r/xboxone Thread Parent Link - twitter.com