That is a great question. Sadly, there is no visible "demarkation". Selecting Advanced vs. Standard Software Updates in the car appears to have no effect on this. But there is a large group of owners who are sent updates to FSD which are not available to everyone. This group is also prevented from updating to new production releases.
Among the 20,000 TeslaFi subscribers, about 7,000 (including myself) are stuck on 2024.3.x but have received 5 or more updates to FSD v12, all on 2022.3, up to 12.3.6 . I call us the testers. Many were on FSD beta back when a high Safety Score was required.
During this same period, the 10,000 plus owners on the production branch has received six new version - 2024.8 and 2024.14, all on FSD 11.4.9 until now with 2024.14.6, which incorporates 12.3.6. This the same version the testers have. It seems this version passed the testing and is becoming widely available.
So, as of right now, the production branch and the tester branch have the same FSD version. This happened before, last December, when FSD beta 11.4.9 was included in the 2023.44 production version. There was speculation that the tester program was over, but then 12.3 was released to testers but no FSD 12 versions went out to the production branch till now.
Of the 2,000 plus installs of 2024.8.9, only 30 of the over 6,000 2024.3 (fsd 12.3.6) are included. So I, for one, am curious if "us testers" will be updated to this version. Over the next few days this will become clear.