The following warning message in CentOS 7.x and RHEL (Red Hat) 7 when you run yum command.
Delta RPMs disabled because /usr/bin/applydeltarpm not installed.
What is it?
Delta rpms created to save bandwidth and speed up download patches and rpm packages. With DRMS, you download only minor changes instead of grabbing full packages. So what basically happens is that you update only the code that changed between the install and the new package.
If you want to enable this you can by using the following command: