<head>
<script src="https://oss.maxcdn.com/libs/respond.js/1.4.2/respond.min.js"></script>
</head>
<body>
<h1 class="text-center">Hello World</h1>
<!-- jQuery -->
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
<!-- Bootstrap JavaScript -->
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
</body>
</html>
body标签内的jquery和head标签内的jquery有什么区别？