URL vs URN in Desktop Shortcuts

Can anyone explain the difference between a URL and URN in ProjectWise.  Also are there any issues to be concerned about with changing the default User Interface setting to Use URN Links rather than URL

The reason being is we are starting to have problems with creating shortcuts to folders because of to many characters in the path.  We have users who like to use sentences to name a folder (or file names) and like to have several subfolders.  Using Copy URL doesn't work with total charcters of more than 256 where URN does for whatever reason.

Thank you,

Bob Hanson