If you will not consider the internal upgrade as a differences among those phones then no. However, the Xr has only a single camera compare to dual camera for the rest of the new iphone X line up. The Xs max is really big. Apple said during the unveiling that the camera on the new Xs series are made with additional enhancement. There is no really significant differences that may look the previous iPhone X to be obsolete.
The only thing that is significantly different is the camera. The specifications are better also. They look identically the same, just the dimensions on the Xs Max are bigger. No significant changes made.
I legit thought that the difference would be in physical sizes of the device. XS made me think of Extra Small, and then I didn't really read the other ones and automatically thought of S, M, L, and XL.
But I think it won't take long before Apple will make 3 of the same device, but with a difference in size, because not everyone has the same pocket size.