Apparently there is no difference:
(document.location === window.location) == true
but it is better coding practice to use window.location.href over document.location.href, don't ask me why but that's the way it is. ;)
In a page using frames, does not document.location refer to each individual frame, and window.location refer to the entire window? You can, for instance, change the content of one frame with:
document.location.href = "foo.htm"
whereas on the same page
window.location.href = "foo.htm"
would change the content of the entire window.
But I may be wrong.
You're wrong =), window.location.href will also change the current frame.
Huh. I keep forgetting not to try to apply actual logic to programming/scripting :)