title: Which is faster: Union or Concat?
body: <p>Which is faster: <code>Union</code> or <code>Concat</code>?</p>
  
  <p>I don't care about the order of the elements.</p>
  
  <p><a href="https://docs.microsoft.com/en-us/dotnet/api/system.linq.enumerable.union" rel="nofollow noreferrer">Enumerable.Union Method</a></p>
  
  <p><a href="https://docs.microsoft.com/en-us/dotnet/api/system.linq.enumerable.concat" rel="nofollow noreferrer">Enumerable.Concat Method</a></p>