There is a significant differance between the behaviour of the drupal edit books admin pages and the drupal menus admin pages.  Specifically the delete link does very different things.

Drupal -> Admin -> Menus -> Menuname (edit)

Drupal -> Admin -> Books -> Bookname (edit order and titles)

The delete buttons on the lists of items in these two core drupal module do very different things.  Clicking delete in the edit list in the book module deletes the node, whereas clicking on delete in the menu module just deletes the menu item and leaves the node in place.