yum install package …..
Yum will check the repository for the package if it finds the package it will install the latest version, pulling in dependencies if needed.
yum remove package ….
Yum will remove the package named by you from your system. If any other package depends on the package then yum will prompt you and gives the option to remove those package too. –yum update package ……
•yum check the repository for the updated version of the package and then install them. If when no package are specified then yum search for updates to all of your currently installed packages.