Sortable vs. Swappable

HTML

<html>
<head>
    <script type="text/javascript">
        $(document).ready(function() {
            $("ul").swappable();
        });
    </script>

</head>
<body>
    <form>
    <ul id="wrapper">
        <li id='one'>
            <div style="width: 100px; height: 100px; border: 1px solid green">
                one<br /></div>
        </li>
        <li id='two'>
            <div style="width: 110px; height: 110px; border: 1px solid red">
                two<br /></div>
        </li>
    </ul>
    <br />
    </form>
</body>
</html>