Upstart and SysVinit
From DikapediaV2
/etc/init is where the upstart init configs live. While they are not scripts themselves, they essentially execute whatever is required to replace sysvinit scripts.
Short story: /etc/init/name.conf will get picked up. It will be used automatically as their 'start on' stanzas control and/or manually by you. And it will put a log in /var/log/upstart/name.log
In Red Hat Enterprise Linux 6, init from the sysvinit package has been replaced with Upstart, an event-based init system.
/etc/init.d is where all the traditional sysvinit scripts and the backward compatible scripts for upstart live.
https://helpful.knobs-dials.com/index.php/Upstart_notes http://v0clinux.blogspot.com/2017/02/list-services-on-startup-initctl-list.html