That table doesn't have greens for apple clang that are missing for regular clang. As far as I know they take some time integrating upstream llvm changes, so the two columns are due to that.
Historically they've been very good about upstreaming. Sometimes it takes a while, but so far everything made it to the public repo.
Definitely got sympathy for that position. Upstreaming changes often takes a long time to get across context, get community buy in to changes, get approval cut a release, whereas internally, it's often just a code review, which can be prioritised according to business needs.
It's quite common for long standing forks to exist, where changes get pushed upstream from the fork, and the fork gets periodically re-cut.
Historically they've been very good about upstreaming. Sometimes it takes a while, but so far everything made it to the public repo.