The author seems confused. Launchd is a service for starting processes (on boot, on other events, or on a schedule), Centralized Task Scheduling (CTS) is a low-level API used only by developers writing native code to perform tasks within a process [0]. CTS can only be used by a running process while launchd is a running process you can instruct by loading .plist files (normally they're only loaded at boot from LaunchAgent/ and LaunchDaemon/ directories).

[0] https://developer.apple.com/library/content/documentation/Pe...