comparing nodesets to each other

Hello,

I currently have to compare two nodelist to each other for differences.
I have in one XML file a structure 'before' and a structure 'after'. Let's
say a recipe and a variation of this recipe. I now need to pick out all
differences, for to mark them in my output report, like the diff command
does. If I found a difference I need to pick out some attributes and values
from this and it's child nodes.

this is my current [not working] idea:

   <xsl:template name="recipe-compare">
      <xsl:param name="pattern"/>
      <xsl:param name="recipe"/>
      <xsl:variable name="variation">
      <xsl:for-each select="$pattern">
         <xsl:variable name="current-findnumber"
select="./Attribute[@Name='FindNumber']/Value"/>
         <xsl:variable name="compare-node">
            <xsl:for-each select="$recipe">
               <xsl:if test="./Attribute[@Name='FindNumber']/Value =
$current-findnumber">
                  <xsl:copy-of select="."/>               
               </xsl:if>
            </xsl:for-each>
         </xsl:variable>
         <xsl:if test=". != $compare-node">
            <xsl:copy-of select="."/>
            <xsl:attribute name="different">current</xsl:attribute>
         </xsl:if>
      </xsl:for-each>
      <xsl:for-each select="$recipe">
         <xsl:variable name="current-findnumber"
select="./Attribute[@Name='FindNumber']/Value"/>
         <xsl:variable name="compare-node">
            <xsl:for-each select="$pattern">
               <xsl:if test="./Attribute[@Name='FindNumber']/Value =
$current-findnumber">
                  <xsl:copy-of select="."/>               
               </xsl:if>
            </xsl:for-each>
         </xsl:variable>
         <xsl:if test=". != $compare-node">
            <xsl:copy-of select="."/>
            <xsl:attribute name="different">pattern</xsl:attribute>
         </xsl:if>
      </xsl:for-each>
      </xsl:variable>
      <xsl:for-each select="$variation">
         <xsl:sort select="./Attribute[@Name='FindNumber']/Value"/>
      <fo:table-row>
         <xsl:choose>
            <xsl:when test="@different = 'current'">
               <fo:table-cell><fo:block><xsl:value-of
select="./object/Attribute[@Name='PartNumber']/Value"/></fo:block></fo:table-cell>
               <fo:table-cell><fo:block>100</fo:block></fo:table-cell>
               <fo:table-cell></fo:table-cell>
            </xsl:when>
            <xsl:otherwise>
               <fo:table-cell><fo:block><xsl:value-of
select="./object/Attribute[@Name='PartNumber']/Value"/></fo:block></fo:table-cell>
               <fo:table-cell><fo:block>100</fo:block></fo:table-cell>
               <fo:table-cell></fo:table-cell>            
            </xsl:otherwise>
         </xsl:choose>
         </fo:table-row>
      </xsl:for-each>
   </xsl:template>

Still learning... Any suggestion or correction highly appreciated...

Regards,
Kai