The release features all the updates and goodness packaged up with the other MX-21 releases, but with a 5.14 kernel and updated mesa, xorg and vulkan drivers to produce a graphic stack more in line with newer hardware, along with a few recompiled applications that utilize the later kernel.
“AHS” by design is a little more on the edge, and not as tested as our primary releases, and the idea is that it will receive updates to the graphics stack over time, so for those that don’t need the newer open source graphics stack, there is little point is using AHS.
One known issue for older systems, particularly with intel-based graphics, is with suspend-to-ram, or at least resuming after suspend. If that feature is important to you and your PC can otherwise use the 5.10 kernel from the main releases, then sticking with the main releases or at least the 5.10 kernels is probably the way to go. (This is how the KDE/plasma release of MX-21 is set up right now).