title: what's the differnece between the 'gulp default task' and 'run-sequence npm modules'?
body: <p>what's the difference between using 'gulp default task' and 'run-sequence npm modules if i have two tasks to execute,the result was the same.so i have no idea why should use 'run-sequence'?</p>
  
  <p>1.gulp default task<br/>
  <code>gulp.task('default',['task1','task2']);</code></p>
  
  <p>2.'run sequence npm modules'<br/>
  <code>var runSequence = require('run-sequence');
      gulp.task('default', function(callback) {
          runSequence('task1', 'task2', callback);
      });
  </code></p>
  
  <p>i'm new in gulp,i saw the tutorial video online,and they teach to use 'run-sequence module' to advance the gulp skill,so i have got the question.</p>