Grumpyfish says: RPM was popularized by Redhat (of course), so many of the ones derived from Redhat (Fedora, Centos, etc.) continue to use RPM or yum for package management. Apt grew out of the Debian system. So you can largely use them to trace the “histories” of various structures. Much of this actually has to do with how file systems are set up. For instance, Redhat and siblings use /etc/sysconfig/ for much of the configuration files, while Debian and siblings keep most of those files in subfolders under /etc/ These low-level organization choices tend to cause people to pick one or the other. I grew up on Slackware, then after 4-years without Linux went back to it via Debian, but have moved to CentOS on my production machines. The Debian -> CentOS shift involved a lot of muscle memory retraining.