Launcher doesn't change the game itself which is still a sort of a Windows version run through Wine. What is changed is Wine configuration and third-party plugins if you are into that. And AFAIK it allows using a Windows license instead of having to use a Mac one (and you can't have both licenses for one account if I recall correctly).
Compared to WoW native Apple silicon version of the game the FF14 on Apple silicon runs way worse than natively on Windows.
Square Enix offers Final Fantasy XIV for macOS via an official launcher, but it is just a wrapper and a poorly optimized and outdated one at that. The folks at XIV on Mac offer an open source alternative written in Swift that works natively on Apple silicon Macs with much improved game performance and support for the Metal 2 API.