Upgrading RPM Packages
The upgrade of RPM packages with YUM is done with the command “yum upgrade”. As with the update command, you can optionally specify package names, wildcards for package names or file names. Without further arguments, all installed RPM packages for which a newer version is available in the repositories will be upgraded.
Upgrading with “yum upgrade” is identical to updating with the command “yum update –obsoletes”. This means that, in contrast to an update, obsolete RPM packages are removed during an upgrade; during an update, they remain installed. In most cases there is no difference between “yum upgrade” and “yum update”, as obsolete RPM packages are rarely present.