What is RPM?
RPM stands for Red Hat Package Manager. It was developed by Red Hat that found widespread acceptance in many Linux distros. This is a command-line tool that you can use to install, delete, update packages in your OS.
What is YUM?
The Yellowdog Updater Modified (yum), which was originally developed to manage Red Hat Linux systems at Duke University’s Physics department, is another open source command-line package management utility for computers running the Linux operating system which use the RPM Package Manager.
You can install software on your Linux machine using either of them if it is an RPM-based distro and not a Debian system. For Debian, you would use tools like apt, apt-get, dpkg.
Difference between RPM and YUM
The biggest problem with the RPM is “Dependency Hell”. This problem occurs with packages that depend on a lot of other packages, some of those packages also depend on some other packages. You must install all dependencies for the program to work correctly. RPM is unable to do this for you automatically. Note: Although it can’t auto-install dependencies, RPM will still warn you about them.
YUM can check for all the dependencies of a package and install them for you prior to installing the package that you wanted to install in the first place. You only need to know the name of the package you want to install, you don’t have to worry about whether the pre-requisite packages have been installed or not.
Both tools can perform an install. RPM will let you install multiple versions simultaneously while YUM will tell you that that package is already installed.
More info on YUM and RPM Package Management.
Hope this helps.