I may be wrong, but I thought the mentioned AUR package (palemoon-bin) is
just a repack of the official binaries, and the Manjaro package is not.
As for the AUR package "palemoon-bin": I've never used it (yet), but there's these two lines in the PKGBUILD file:
Unless I'm completely wrong (which may very well be the case, because I'm actually not very familiar with the structure of PKGBUILD files), this means that installing this package will simply download the official binaries from linux.palemoon.org.
It's different for other packages, of course (such as "palemoon" without "-bin", which I assume will compile Pale Moon from the source code locally on your computer).
As for the Manjaro package, as JustOff already mentioned, there are these two lines "Palemoon for Manjaro" and "Manjaro - Rolling" in "Help" > "About Pale Moon". That's why I assumed that the Manjaro packages are custom builds.