Concept of Window Manager vs Desktop Environment
 

I'm a bit confused on the concept of a desktop environment vs a window manager. I'm looking to run an extremely lightweight desktop so I'm looking into fluxbox or icewm. However I notice they are called window managers as opposed to desktops. Also I see icewem touts "support" for gnome desktop. What does this exactly mean? So is it possible to install only icewm and have it function as a working desktop (assuming I have the needed gnome and kde libraries) without the fullblown gnome or kde? I'm just looking for someone to clear up what these terms mean. Thanks

Window Manager = software to manage/maintain windows including functionality, look, feel, etc.

Desktop Environment = compilation of lots of software packages into a "complete" environment with tools to manage various system settings. All desktop environments usually incorporate a window manager, e.g. metacity, fluxbox, sawfish, etc.