Sometimes it is useful to compare two versions of the same Latex document in a way that highlights changes, just as the track changes module of MSWord would do (e.g., when working with collaborators, after revising a paper, or just if you are in doubt of which document is the most recent.) It turns out that issuing the command (for Windows users, it is already included in the Miktex distribution of latex) :
> latexdiff-so version1.tex version2.tex > diff.tex
from the DOS command line interface, will compare the original document "version1" against the modified "version2" and output a document highlighting changes as "diff".
The only requirement that you will have is a Perl interpreter that, for Windows users, can be obtained by installing the suite Rtools (incidentally, this furnishes you with all you need to build native R in MS Windows.)
Important! For running the command above you must have Perl in the Windows Path. The Rtool default installation asks you for permission for such a modification --- if you do not have administrator's privileges, you have to do this by hand using the user's path in the environmental variables option of the MS Windows system dialog.