In order to see differences between two latex generated documents, one can use a program called latexdiff: https://www.sharelatex.com/blog/2013/02/16/using-latexdiff-for-marking-c...
latexdiff is a Perl script and requires an installation of Perl 5.8 or higher.
If you are a Windows user, you will have to go through the following setup to get latexdiff working on your machine:
1) Install Perl
2) Download latexdiff from CTAN (Comprehensive TeX Archive Network)
3) Unzip the latexdiff files and copy them to the Perl > bin folder (default installation in C: drive)
Mac OS X includes an installation of Perl and no additional setup is required. latexdiff can be found in any CTAN repository in TeX Live Utility.
It is important to use --flatten which makes latexdiff recursively operate on any included .tex files. Then use command line like that:
latexdiff --flatten v1.tex v2.tex > diff.tex
where v1.tex is one version (older) and v2.tex is changed (newer) version. diff.tex is then a tex file that is produces as an output.