Ediff is described as 'comprehensive visual interface to Unix diff and patch utilities' and is an app in the File Management category. There are more than 10 alternatives to Ediff for a variety of platforms, including Windows, Linux, Mac, Online / Web-based and BSD. The best alternative is Meld, which is both free and Open Source. Other great apps like Ediff are WinMerge (Free, Open Source), Beyond Compare (Paid), KDiff3 (Free, Open Source) and Compare (Free, Open Source).
Beyond Compare allows you to compare files and folders. By using simple, powerful commands you can focus on the differences you're interested in and ignore those you're not. You can then merge the changes, synchronize your files, and generate reports for your records.
Meld is a visual diff and merge tool targeted at developers. Meld helps you compare files, directories, and version controlled projects. It provides two- and three-way comparison of both files and directories, and has support for many popular version control systems.
tkdiff is a graphical diff viewer based on the Tk framework. It is capable of inter-operating with source-control systems like CVS and Subversion to show differences between a local copy and a repository version.