Output buffer versus file_get_contents in PHP

What are the differences between these two ways to get the file content? Which one is better and more effective? I think they will both get the same results, but I really don't know which method is better.

For example.

This code uses output buffering to get the contents of the file:

ob_start();
include('foo/bar.tpl');
$output .= ob_get_contents();
ob_end_clean();

      

        
        
        
      

    

This code uses file_get_contents and gets the same results.

$output = file_get_contents('foo/bar.tpl');