http://fileinfo.com/extension/drpm
Definition——File used by Linux operating systems for installing software; similar to an
.RPM file, but is significantly smaller in file size because it only includes the files required since a prior RPM package was installed.
More Information——Delta RPMs are used by software managers such as Fedora's Presto plugin for yum. When this plugin downloads a DRPM file, it uses existing RPM package information
on the system as well as the DRPM file to reconstruct a full RPM. By using this method, files already on the local system do not have to be redownloaded.