Win32::ChangeNotify does not provide that information. You would have to figure it out yourself by listing the directory before and after the notification and comparing the results. There is another module Win32::AdvNotify which, if you can find the module (update: here is a link), would provide that information, but keep in mind that that module is long unsupported, no source is available, and the author is MIA.
BTW, I could not get POE::Component::Win32::ChangeNotify to work, have you had any better luck? For me, the program exits before it ever calls the notification routine.