The GNU wdiff program is a front end to diff for comparing files on a word per word basis. A word is anything between whitespace. This is useful for comparing two texts in which a few words have been changed and for which paragraphs have been refilled. It works by creating two temporary files, one word per line, and then executes diff on these files. It collects the diff output and uses it to produce a nicer display of word differences between the original files.