Well Rob I am assuming here you are completely newbee, so I am stating some fundamentals here:
1. XSL is used as template to generate html document.
In XSL you have various place holders which specify dynamic data.
Now to use this template, a XML is mapped upon XSL for this tag hirarchy XML should correspond to XSL place holders.
The combined output is html. This whole api is availble in J2SE only, so you can generate html pages out of desktop application.
2. JSP technology is based upon
java servlet api. It acts as template to produce html. It is part of
J2EE.
Well, uptil here they seem to be compareable in terms of end result. But, they do not mix/gel togather as purposes of each is different.
A JSP/Servlet is equipped with servlet lifecycle. It has all the fundamental specifications to be developed as a full fleged, dynamic web application.
While, XSL is only for smaller roles like generating a html report from application or likewise.
In short below will nerver gel togather.
<xsl:variable name="test" select="description"/>
<c:set var="message" value="${test}" />