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Pro Creates patches
These patches can be used to apply the differences to the same source file at a different storage location (different folder, different machine).
Pro Compares entiry directory trees
Two directory trees can be compared file by file recursively. All differences are output concisely.
Pro Multiple formats
The difference can be output in formats known as normal, unified, ed, rcs, and side-by-side.
Pro Command Line Interface makes it easy to use for people who work a lot in the terminal
Great for creating patch files, using with other *nix utilities (for example, colordiff). Does not require a GUI.