Hello sh4dow,
The fork has been created back in the Factorio 1.1 days, and received a number of updates that dealt with some issues around leftover placement markers, introducing ability to keep (mostly) undo queue working correctly, adding support for handling the underground belts more consistently etc. To get a good idea on changes made, I suggest having a look at the changelog (particularly prior to 4.0.0 release).
Unfortunately, those changes did not get merged back into the original (revived) mod, and for all the practical purposes you can view the two mods as alternate implementations of the feature at this point. I glanced over the recent changes in the original mod code base, there is a lot of refactoring, and I have not dug into details, so there is a chance lots of these things (especially with some changes in Factorio 2.0) had been implemented there as well.
I think the original mod author might also greatly redo the way the approval works to deal with some of the shortcomings of the current system (that introduces additional force into the game that owns the unapproved entities) - so you might want to keep a look-out on both mods for a while. If the new approach turns out to be superior to the old one (used in the fork), I might end-up dropping Construction Planner Continued at that point (with some migration path), but for now I continue to maintain it.
I do have plans to do some "rebranding" of this fork (like mod thumbnail, probably name too), though, to avoid confusion, just a bit busy with some real-life stuff at the moment.
Not a straightforward answer for you, unfortunately, but there's some history in there which always makes it messy. :)
Best regards,
Branko
