Intel has published an article that looks at the evolution of both Microsoft Windows Mobile (and its previous names) and the parallel evolution in processors that power Windows Mobile devices. The article looks at the different XScale processor families: the PXA27x, PXA26x, and PXA255 families. It’s a good recap of the characteristics of the different processors.
The article might be a little bit older as it does not mention Windows Mobile 2003SE.