title: What is the difference between returning IList vs List, or IEnumerable vs List<Class>. I want to know which is better to return
body: <p>What is the difference between returning IList vs List, or IEnumerable vs List. </p>
  
  <p>I want to know which is better to return.</p>
  
  <p>When we need to use one, what effect will it have on performance?</p>