I use an old DOS utility called DIFF, which is pretty good. That is, it's smart enough to recognize differences in sections, rather than just looking at single lines, in your documents. When I invoke the program with no parameters, here is what it says to me.

 Usage: diff file1 file2 [/option /option...]
        where /option is one of the following:
                  /number - to show line numbers
                  /bars - to display change bars
                  /context - to show context