Actually, the question (taken literally) means (to put it bluntly) "what's the difference?"
There is no difference in functionality, so the only thing I can tell you is what I have already mentioned. How can I know that this is not what you want to hear?
Actually, C++0x offers cstdint, so that one could be used.
As far as I have understood Laurent, he doesn't plan to switch to C++0x.
Anyway, I don't know what's wrong with the current sf::Uint32 type. It fulfills its task, what's the point in creating a new dependency?