>>19
Few window managers are designed with clear distinction between the windowing system and the window manager. Every graphical operating system which uses a windows metaphor has some form of window management, however in practice the elements of this functionality vary greatly.
On systems using the X window system, there is a clear distinction between the window manager and the windowing system. Strictly speaking an X window manager does not directly interact with video hardware, mice, or keyboards, which are the responsibility of the X server, but should be the responsibility of the kernel to provide.
Users of the X Window System have the ability to easily use many different window managers such as those included in GNOME, KDE, and many others.
So... window managers are included in GNOME and KDE (therefore, the desktop environment is the same as the window manager) but only someone that uses Windows would "confuse" the two. Great.