“yum upgrade and yum update will perform the same function that update to the latest current version of package. But the difference is Upgrade will delete obsolete packages, while update will preserve them.Jul 3, 2014”
https://unix.stackexchange.com/questions/55777/in-centos-what-is-the-difference-between-yum-update-and-yum-upgrade
3.3. UPDATING PACKAGES FROM THE COMMAND LINE WITH YUM
https://access.redhat.com/documentation/en-us/red_hat_network_satellite/5.5/html/reference_guide/sect-reference_guide-package_updater-updating_packages_from_the_command_line_with_yum
yum install package_name
yum update package_name
yum check-update
yum remove package_name
yum provides package_name
yum search keyword
yum localinstall absolute path to filename
Reference: the above link