title: MongoDb: Difference between $push/$addtoset
body: <p>I read the documentation in the MongoDb and I used a simple proves and I only look that:
  Push is sorting the array but <code>addtoSet</code> isn't it.</p>
  
  <p>For me visually is the same, I don't know the difference.</p>
  
  <p>Could anybody explain me the difference?</p>
  
  <p>Another think if it could be in spanish or in a simple english, i'll aprecite it.</p>