etcupdate(8) vs mergemaster(8)

Afternoon all,

What's the difference between etcupdate(8) and mergemaster(8)? They seem to do very similar things...

While most likely not supported, and therefore for 'play' and research purposes only, I'm interested in updating my /etc files from a release/snapshot tarball, but not really sure of the better tool to use - I'm currently running FreeBSD 11.0-RELEASE-p9 installed from the ISO, so no custom kernel.

I'm struggling to get my head around what each of these tools do, and how they achieve what they do.

Would anyone be able to provide some explanations?

Many thanks,
If you use freebsd-update(8) to update your system you don't need to use either of them, the merging is done automatically by the update process. mergemaster(8) is primarily used when updating your system from source (buildworld and all).
For me the most important detail is that /usr/sbin/mergemaster is part of the base system while sysutils/etcupdate isn't. It's what makes me ignore etcupdate.

As to the other differences, I think their manualpages best describes those.
etcupdate(8) has been part of base since FreeBSD 10.0.
Interesting, then I can only assume it's part of freebsd-update. I update my system by using the source tree and therefor have no need for this, so disabled that. And well... I do have mergemaster on my system but there's no trace of etcupdate.