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.

1  –  Menus Go Goto

  After you have selected a topic from the list of
  additional topics, you can perform a Go To Topic or
  Visit Topic operation on that selection. If no topic is
  selected, these menu items are dimmed. Double clicking
  on the selected topic has the same result as selecting
  a topic and then selecting the Go To Topic menu item.

  If you perform a Go To Topic operation on the
  selection, the current help topic in the Help window is
  replaced by the new topic.

  In the Help system, performing a Go To Topic operation
  is the most common operation. So in Help, selecting
  something from the list of additional topics by double
  clicking MB1 performs a Go To Topic operation.

  See the Visit Topic menu item for the alternative to
  Go To Topic.

2  –  Menus Go Back

  Go Back replaces the current help topic with the
  preceding help topic. It is possible to step back
  through all the help topics you have seen.

  Stepping back through previous topics in this way can
  also be achieved using the Go Back button, which has
  exactly the same function as this menu item, or by
  using the History... menu item from the Search menu.

  Both these methods can be quicker than using this menu
  item, particularly if you want to go a long way back.

3  –  Menus Go Visit

  After you have selected a topic from the list of
  additional topics, you can perform a Visit Topic or Go
  To Topic operation on that selection. If no topic is
  selected, these menu items are dimmed.

  When you perform a Visit Topic operation on a selected
  topic, the Help system displays the new topic in a
  separate window, so that you can see both old and new
  topics at the same time. This makes it possible to read
  two or more help topics simultaneously.

  See the Go To Topic menu item for the alternative to
  Visit Topic.

4  –  Menus Go Gotoover

  Choosing the Go To Overview menu item causes the
  current help topic to be replaced by the Overview help
  topic for the current application. This topic provides
  access to the whole help library for the current
  application.

5  –  Menus Go Visitgloss

  Choosing the Visit Glossary menu item causes the
  current application glossary to be displayed in a
  separate Help window. A term can then be selected from
  the glossary, and its definition is displayed in the
  Glossary window.

  Note: Not all applications use the Glossary menu item.
  In these cases, the Visit Glossary menu item from the
  View menu and the Glossary... menu item from the Help
  menu are dimmed or missing.