title: Pipenv - Pipfile.lock - Difference when updated automatically compared to updated using `lock` command?
body: <p>I read online that <code>Pipfile</code> is always updated automatically whenever a new package is installed/uninstalled/updated.</p>
  
  <p>But I noticed that <code>Pipfile.lock</code> is also updated automatically. Then what difference does it make to <code>Pipfile.lock</code> when it is updated automatically compared to updated using <code>lock</code> command? </p>