jQM - Pageinit and Pagebeforeshow differences

HTML

<link rel="stylesheet" href="http://jeromeetienne.github.com/jquery-mobile-960/css/jquery-mobile-fluid960.css">
<script src="http://timeago.yarp.com/jquery.timeago.js"></script>
<script src="http://imakewebthings.github.com/jquery-waypoints/waypoints.min.js"></script>
<!DOCTYPE html>
<html>
<head>
    <title>jQM Complex Demo</title>
    <meta name="viewport" content="width=device-width; initial-scale=1.0; maximum-scale=1.0; minimum-scale=1.0; user-scalable=no; target-densityDpi=device-dpi"/>
    <link rel="stylesheet" href="http://code.jquery.com/mobile/1.3.2/jquery.mobile-1.3.2.min.css" />
    <script src="http://code.jquery.com/mobile/1.3.2/jquery.mobile-1.3.2.min.js"></script>    
</head>
<body>
    <div data-role="page" id="index">
        <div data-theme="a" data-role="header">
            <h3>
                First Page
            </h3>
            <a href="#second" class="ui-btn-right">Next</a>
        </div>

        <div data-role="content" id="test">
            
        </div>

        <div data-theme="a" data-role="footer" data-position="fixed">

        </div>
    </div> 
    <div data-role="page" id="second">
        <div data-theme="a" data-role="header">
            <h3>
                Second Page
            </h3>
            <a href="#index" class="ui-btn-left">Back</a>
        </div>

        <div data-role="content">

        </div>

        <div data-theme="a" data-role="footer" data-position="fixed">

        </div>
    </div>    
</body>
</html>

JavaScript

$(document).ready(function() {
    $(document).on('pageinit', '#index', function(){       
        alert('Pageinit');
        loadMap();      
    });
    
    /*$(document).on('pagebeforeshow', '#index', function(){       
        alert('Pagebeforeshow');
    });*/
    
    function loadMap() {
      $('#test').html('coucou');
      alert('ok');   
    }
});