Here's bunch of other XML difference tools:
- IBM AlphaWorks XML Diff and Merge Tool - Java based, uses tree matching based on ID attributes or content
- Dommitt Unordered Diff - ignores order of nodes in document (?!), Java based, flattens DOM trees to arrays then does step by step comparison to generate insert, delete, update and nochange operations.
- diffxml - GPL, Java based, algorithm detailed in author's dissertation [postscript]
- XML::SemanticDiff - Perl module, artistic license, event driven parser, seems to handle namespace changes
- DeltaXML - commercial application, Java based, tree matching, root elements must be the same