Features:
Compare text files
Merge file differences
Compare XML files
Compare folders and directories
Compare and merge Office 2007 (OOXML) files
Compare files inside ZIP archive pairs
Compare XML Schemas and create XSLT transformations for XML data files
Database schema differencing with merge options
Compare and merge database tables
Save database comparison files for quick reload
Set XML differencing options
Sync directories in one step
Examine XML files in Grid View
Generate Unix diff-style reports
And much more . . .

Home Page - http://www.altova.com/products/diffdog/diff_merge_tool.html