Package Changes Analyzer (pkgdiff) can compare and show differences between Linux software packages. It supports reading from RPM, DEB, TAR.GZ and other common formats. It's intended for maintainers to test compatibility and consistency between archive versions.
csvdiff is a Perl script to diff/compare two csv files with the possibility to select the separator. Differences will be shown like: "Column XYZ in record 999" is different. After this, the actual and the expected result for this column will be shown
MDR displays unified diff output in a graphical window, highlights changes (new and removed parts) per highlighting. It can be combined with any source control system (it's somewhat like fossils builtin diff --tk, but for git, hg, bzr or svn). It runs on WebKitGtk.
DiffImg computes pixel discrepancies between two image files and displays them as color mask or as yellow/red overlay. It also provides a dual panel display, can compute the mean error, RMS and min/max values, shows an error histogram, or display a slideshow for image directories. This allows for compression level comparisons, or optimizing raytracing parameters.