I started using OpenGL but I have to admit the procedural nature of the API bugs me, being a heavy OOP person. While it's easy enough to find the functions you need, since they are all named accurately to what they do, the convoluted state machine that you end up having to manipulate is difficult to reference for me. I started XNA recently and like the approach it gives, I may move to DirectX hopefully without too much effort. Personally I don't mind it not being portable though I've played some great games that are done in OpenGL.
The main difference is if you need tools that do something like load textures, load 3d models, in OpenGL you merely need to find a library that does it and include it in your project. Most of that "basic" functionality as far as gaming goes is already implemented. I think that's what Elysia means by more evolved, it just has more tools that one would need when using a 3D programming framework.