https://wiki.manjaro.org/index.php/Manjaro:A_Different_Kind_of_Beast

Although Manjaro is Arch-based and Arch compatible, it is not Arch.

Manjaro package repository

Stable branch - There is no solid rule indicating when Stable branch is snapped from testing. It can be anything from one to four weeks....

Testing branch - Testing branch is snapped from unstable at irregular intervals - ...

Unstable branch - Unstable branch is synced several times daily from Arch stable

Manjaro Unstable is Arch Stable