@mms I'd say variations on a theme. FreeBSD and NetBSD both have the defaults in /etc/defaults/rc.conf and you edit /etc/rc.conf while OpenBSD has the defaults in /etc/rc.conf and you edit /etc/rc.conf.local, close enough that it's obvious they share a common origin.
@pitrh@mms FreeBSD also has /etc/rc.conf.local now too so /etc/rc.conf can be controlled by the OS/distro/applicance flavor and the end user/admin can have their specific changes in the .local
@mms OpenBSD forked from NetBSD back in 1995. There has been parallel development ever since, so there will be differences. But I do not think any of them went as far as replacing the entire init system.