Saves the current widget layout and allows the layout to be restored at a later date.
No. Only widget layout is saved. Widget layout is the widget's sidebar location, as well as its order within the sidebar.
Widgets that are deleted can not be restored because widget content/settings are not saved. Dragging a widget back into the "Available Widgets" area effectively deletes the widget. In order to remove a widget from view, but keep its content, drag it into the "Inactive Widgets" area. This will ensure that the widget 'instance' is not deleted, and can be restored in different layouts.