One tool that works better than diff (in my opinion) is latexdiff http://www.ctan.org/tex-archive/support/latexdiff/ . The advantage is that the result is a tex file with the deleted text struck-out and the added text underlined. It also uses color. the reason this is nice is for collaborating with people that don't want to use your version control method. once you get the file back from them you simply commit it to the repository and then use latexdiff-vc to see the differences. One of my collaborators likes writing latex in one long line (one line per paragraph) so using regular diff is almost useless with him....