title: What is the difference between IEqualityComparer<T> and IEquatable<T>?
body: <p>I want to understand the scenarios where <a href="http://msdn.microsoft.com/en-us/library/ms132151.aspx" rel="noreferrer"><code>IEqualityComparer&lt;T&gt;</code></a> and <a href="http://msdn.microsoft.com/en-us/library/ms131187.aspx" rel="noreferrer"><code>IEquatable&lt;T&gt;</code></a> should be used.
  The MSDN documentation for both looks very similar. </p>