title: What is the difference for locale: zh_CN, zh_CN.utf8 and zh_CN.UTF-8
body: <p>For locale: zh_CN, zh_CN.utf8 and zh_CN.UTF-8, are they same?  </p>
  
  <ul>
  <li>If they are same, why we need to use different name?</li>
  <li>If they are not, they should be used in what kind of situation? </li>
  </ul>