When an upgrade includes changes to a default configuration file, the package will write either a .rpmnew or a .rpmsave file instead of overwriting the configuration file on your system. Which file a package creates is up to the discretion of the package maintainer.

From “Dealing with .rpmnew and .rpmsave files” By Bruce Byfield:

An .rpmnew file contains the new default configuration file and leaves your original configuration file untouched. By contrast, and .rpmsave file is a copy of your original configuration file, which has been replaced by the new default file.

The following script can be helpful to find (and possibly merge) those files with your original configuration

for a in $(find /etc /var -name '*.rpm?*'); do diff -u $a ${a%.rpm?*}; done

You may also want to check on yum-merge-conf, a yum plugin to merge configuration files.