This depends on the pkg maintainer. They do it as per their convenience of pkging, compiling and testing pkg stability on the arch.
For Manjaro Arm it get updated approximately at the same time or with a slight difference in release date.
This is 2 different arch so 2 different team working on their respective arch. There are chances of having apps look different in both arch as it all depends on how the maintainer maintains it.
Do not expect arm to be exactly like x86 as not everything is ported to arm yet. Example, apps like anydesk, teamviewer and many more…