title: Difference between moment.utc(date) and moment(date).utc()
body: <p>Trying to understand the behaviour and difference between: </p>
  
  <p><code>moment.utc(date) and moment(date).utc()</code></p>
  
  <p>Using '2018-05-31' as a param: </p>
  
  <p><code>moment.utc('2018-05-31').format()</code> will give:</p>
  
  <blockquote>
    <p>‌2018-05-31T00:00:00Z</p>
  </blockquote>
  
  <p>while <code>moment('2018-05-31').utc().format()</code> will give:</p>
  
  <blockquote>
    <p>2018-05-31T04:00:00Z</p>
  </blockquote>
  
  <p>I am executing both in EST timezone. </p>