With WebDAV you can access the Drive app files in the same way as when accessing local files on your disk. Compared with the access from the Groupware GUI, WebDAV has advantages and disadvantages:
The advantage is the quick and direct access with a file browser e.g.: Windows Explorer. You need not be logged in to the Groupware GUI.
The disadvantage is that you can only see the current document version. Neither the version history nor additional information, like comments, are displayed.
Warning: If you delete a file with WebDAV, all versions will be lost, not only the current version.