priefaces && JSF

<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:h="http://java.sun.com/jsf/html"
      xmlns:f="http://java.sun.com/jsf/core"
      xmlns:p="http://primefaces.org/ui">
<h:head>
</h:head>
    <h:body>
       <p:tagCloud model="#{tagCloudBean.model}" />
    </h:body>
</html>
<ui:composition xmlns="http://www.w3.org/1999/xhtml"
                xmlns:ui="http://java.sun.com/jsf/facelets"
                xmlns:h="http://java.sun.com/jsf/html"
                xmlns:p="http://primefaces.org/ui">    <ui:define name="content">
            <h:form enctype="multipart/form-data">
               <p:tagCloud model="#{tagCloudBean.model}" />
            </h:form>
    </ui:define>
</ui:composition>
有什么区别吗 为什么一个显示一个不显示UIHTMLJSFprimefacesjavaweb