Swift Compare is an excellent program with which you can visually compare the content of two files. Its simple interface colours all the lines that are different in the files, so you`ll have no problems detecting modifications and editions.
It is also possible to compare the existing files in folders, so if you`re a programmer and want to see which files have been modified since the last version, it will take you seconds to see.
Swift Compare also lets you synchronize folders and files, so that this way you always have the most up to date version in each of them.
Also, among the options there are a multitude of personalizable adjustments, so you can adapt the program to your needs, ignoring blank spaces in the comparisons, tabulations, etc.