title: Difference between port and listener in MQTT
body: <p>I have installed mosquitto client for MQTT on my local machine.
  I have below configuration:</p>
  
  <pre><code>listener 1883
  protocol mqtt
  listener 9001
  protocol websockets
  </code></pre>
  
  <p>What is the difference between running client on mqtt and websockets. Also what is the difference if i change listener to port?</p>