Test::Differences Perl module contains test strings and data structures and show differences if not ok.

Schema-compare is a script that will compares two database schema and show the differences side-by-side. Schema-compare can also generate SQL statements that will alter the old database to match the schema of the new database.

Algorithm::DiffOld is a Perl module to compute `intelligent differences between two files / lists but use the old (<=0.59) interface. NOTE This has been provided as part of the Algorithm::Diff package by Ned Konz.

LibXDiff implements basic and yet complete functionalities to create file differences/patches to both binary and text files. The library uses memory files as file abstraction to achieve both performance and portability.

sqlt-diff is a Perl module that can find the differences b/w two schemas.

Mptn project is a library providing a pattern matching mechanism similar to regular expressions, but with several differences making it more suitable for building a morphological analyzer.

Algorithm::Diff is a Perl module to compute `intelligent differences between two files / lists.

fldiff is a graphical diff program that shows the differences between two files/directories, or a file/directory and a CVS or Subversion repository.

PCRE library is a set of functions that implement regular expression pattern matching using the same syntax and semantics as Perl 5, with just a few differences. The current implementation corresponds to Perl 5.005.

Visual difference metrics can predict whether differences between two images are visible to the human observer or not.

finds differences between two directories and storing all new/updates files in a new directory. It is a simple command line tool and Ant task. It is extremely useful for creating incremental backups and updating big web-sites.

robots.txt is a script in PHP that acts like a normal robots.txt file, but with a few differences. When a Spider attempts to access robots.txt, the script will "disallow" access to a list of pre-defined directories.

Xfdiff project is graphic interface to the GNU diff and patch commands. With this utility, you can view differences side by side for files or directories.

Libptytty is a small library that offers pseudo-TTY management in an OS-independent way. It was created out of frustration over the many differences of PTY/TTY handling in different operating systems for use inside "rxvt-unicode".

Freedroid RPG project is an extension/modification of the classical Freedroid engine into an RPG. The main differences to the classical version are as follows: &middot; The Tux is the main character of the rpg.

FindIt NIX project is a clone of a great find-the-difference game. FindItNIX is a clone of the Windows game FindItXP. The goal is to spot the 5 differences between 2 images within a certain amount of time.

LEAF Bering-uClibc is based on the well-known Bering distribution from Jacques Nilo and Erik Wolzak and provide the same features and functionality in the base. Anyway there are some differences with the original Bering release.

xmlTreeNav is a XML viewer with several features. It can show the differences between two XML files (by using software based on the libxmldiff project).

JSBlend is a cross-platform, web-based file comparison and merge tool written mostly in Javascript. The tool can display differences in two files and allow the user to selectively merge them by editing one of the files.

Tofuhunt is a "whats wrong with this picture?" game for Linux. Two pictures come up and you are to find the differences or a tofu in the pictures. You can also make your own pictures.