It might be worth it, for any newcomers who browse through these forums, to quickly explain the difference. A window manager, e.g.
x11-wm/openbox, just manages the windows -- while they may have some enhancements, generally, they just give you an X environment, open windows of any GUI applications or X terminals.
A desktop environment, e.g.
x11/gnome2, will have its own tools to not only open applications, but also to do things like install printers, manage sound levels, etc. For example, if running Openbox, you might install a printer using the
print/cups program. If running GNOME or KDE, they will have their own printer installation and configuration tool -- it might use CUPS as a back end, but it will have its own graphic interface to use. The upside is that it can, when it works properly, simplify installation of a printer and save time. The downside is that it adds another layer than can possibly break and if something does go wrong, it will be harder to find and fix. (Printer configuration is just one example, network configuration and user management are others.)