I split your post from the original "
OSX GAs (VBoxDarwinAdditions.pkg): what is working" thread. You're talking about the
6.1.0rc1 GAs, your questions do not belong in the "OSX Hosts" area anymore...
SteveMacGeek wrote:Does the release of 6.1.0 RC 1 change the Guest additions situation for MacOS?
No.
SteveMacGeek wrote:the docs are still vague about Mojave 10.14 guests
Only guests up to 10.13 are supported. 10.14/15 are not supported yet. I don't think that there's any vagueness in there. If there is, please post the appropriate section so that it can be addressed.
SteveMacGeek wrote:say the VBoxGuestAdditions aren't supported for MacOS
They need to add a chapter for OSX GAs. But I guess they're way too experimental and half-baked at this point to have their own chapter in the User Manual...
SteveMacGeek wrote:Otherwise, why have the extension pack posted for MacOS
Otherwise, why have the Guest Additions posted for Every Guest
There, I fixed it for you.

You're pointing to the Guest Additions (GAs) ISO, not the Extension Pack. And there is a single GAs ISO, for every possible Guest that is supported by the GAs.
SteveMacGeek wrote:what are the differences between these two downloads
They're identical. One has simply the revision number on its filename.