Difference between router path and link path? I have recently started looking into the drupal menu system. I am not able to understand the difference between a router_path and the link_path. Both point to the same location in my installation.
Pro Drupal Development, Second Edition describes them as:


  menu_links.link_path is the Drupal path or external path this link
  points to.
  
  menu_links.router_path is for links corresponding to a Drupal path
  (0 means external), this connects the link to a menu_router.path for
  joins.