Process monitoring, in the basic sense, is seeing if a process is running. You mean how they handle dependency trees/graphs ? From what i just read sysD targets are groups that can have other groups in them (aka inherit, aka "services", aka compose). I wonder if that is the core of the problem. Not that i care, that's the hole they dug for themselves when they insisted only pid EINS can orchestrate cgroups (didn't use to be).
Either way, in the overwhelming majority of use cases they are practically the same.
Bdw, i didn't downvote you. I reserve it only for the most irrational fans, aka parroting fanboys.