Launch an external diff tool like WinMerge in Eclipse
...After you open two versions of a file in the internal eclipse compare editor, this plugin either opens an external diff tool automatically or you can choose that this plugin opens the external diff tool after you press a button in the toolbar of the internal compare editor.
Furthermore the plugin can (optional) format java code before the compare. This simplifies the compare if the code of 2 versions of a file is different formatted.