I agree its hard to get across exactly what I mean, I'll try and expain it using the snipping tool:
Here I'm moving the window on the left over towards the right side of the screen. As soon as it gets to this point, the windows jumps across and skips the remaining space and aligns with the control panel window as in the next screenshot (It's as if they are magnetic - they snap together as soon as they get relatively close). It does this with the sides of the screen and with the task bar as well. This means that it isn't possible to have windows slightly overlapping without them aligning themselves.
I know this seems like a very trivial thing but it is so much smoother with this turned off. Hopefully I have expained it more clearly, thanks for your patience and replies.