When most people want to close or restart Explorer they just terminate the Explorer task via the Task Manager or via a call to the Windows function TerminateProcess. Explorer is however a "regular" Windows application that shows the desktop and all open folder windows. So when it is terminated it won't get a chance to save it's settings. This may cause some modified Explorer settings not to be preserved when Explorer restarts again. On Windows XP, Vista and 7 this includes e.g. the list of opened folders.
However, ShellDispenser-Dev closes Explorer in a more gentle way, so that Explorer gets plenty of opportunity to save it's settings.