title: devise rails current_user vs user_signed_in?
body: <p>I am using Devise on Rails 4.1
  My question is regarding the helpers and how they relate to sessions.
  current_user : tells you if there is a user session available for the user.
  user_signed_in: tells you if the user is authenticated.</p>
  
  <p>I cannot understand how a there can be a current_user if the user_signed_in? is false?</p>
  
  <p>What is the difference between the two methods, and how does it relate to sessions.</p>
  
  <p>THanks.
  Richard Madson</p>