The difference between Go To Topic and Visit Topic is
  that Go To Topic replaces the current help topic with
  a new one, while Visit Topic creates a new window for
  the new topic, so that both the current topic and the
  new one are displayed simultaneously.

  Overview is the top level help topic, and the Glossary
  is a list of terms specific to the application.

  For more information on any View menu item, select the
  appropriate menu item from the list below.