I should have looked at the posting date!
The basic difference is that there is no tone mapping in exposure blending. It is similar, but not identical, to manual "HDR" with layers, where you stack images with several exposures and use masks to retain only well exposed areas. Check out the link in my earlier posting, and compare the wikipedia entry on tone mapping.
In terms of the two images I posted: the point they illustrate is that exposure blending produced entirely natural colors, with no tweaking needed. HDR Pro (in CS5) didn't. Perhaps I could have made the HDR image similar, but it wouldn't have been simple--e.g., I would have had to mess around with the color balance in the sky to get rid of the turquoise tint and the rocks to get rid of the unnatural reddish tint. And why bother? If all you want is to combine different exposures, exposure blending does it simply. On the other hand, lots of people really like the effects you can get with tone mapping. To each his or her own.
I don't own photomatix, but someone recently told me that one of the options it provides is exposure fusion.