Install an utility like Meld (there are other utilities for doing this, too, but I like Meld since it doesn't have KDE/GNOME dependencies) and use it for visually diffing/merging the files.
Meld is a visual diff and merge tool targeted at developers. Meld helps you compare files, directories, and version controlled projects. It provides two- and three-way comparison of both files and directories, and has support for many popular version control systems.
