What is the difference between a StackPanel and DockPanel in WPF?

What can a DockPanel do that a StackPanel cannot? If anyone has an image of something that can be achieved with a StackPanel, but not a DockPanel, than that would be great.

Stack Panel: The StackPanel, as the name implies, arranges content either horizontally or vertically. Vertical is the default, but this can be changed using the Orientation property. Content is automatically stretched based on the orientation (see screenshot below), and this can be controlled by changing the HorizontalAlignment or VerticalAlignment properties.

Dock Panel: The DockPanel is used to anchor elements to the edges of the container, and is a good choice to set up the overall structure of the application UI. Elements are docked using the DockPanel.Dock attached property. The order that elements are docked determines the layout.