title: difference between pub-sub and push-pull pattern in zeroMq
body: <p>This two images are from <a href="http://zguide.zeromq.org/page:all" rel="noreferrer">http://zguide.zeromq.org/page:all</a>.</p>
  
  <p>What is the difference between this two pattern if we ignore sink in push-pull pattern ?
  Is there a difference in how a message gets transfer, if yes what is the difference ?</p>
  
  <p><img src="https://github.com/imatix/zguide/raw/master/images/fig4.png" alt="">
  <img src="https://github.com/imatix/zguide/raw/master/images/fig5.png" alt=""></p>