Disabling android built-in launcher Can I ask If what will be the effects if I will Disable my Built-in android launcher and replace with the launcher that I have downloaded??
A smartphone is capable of performing several functions using a single device. That includes calls, messages, photo, video, internet, social media etc. So, if a manufacturer releases a phone, it should have these default features. That means, after device power on you can see phone app for call utility, camera app for photo, video capture, default keyboard for typing words. If anyone is missing, it would affect device functionality. Likewise, all applications arrangement/displaying  app is called launcher. These are the basic apps required for functioning and they are called system apps.   

Android also allows you to install other apps that provides similar functions as I have mentioned above. They are called user apps. 

For example, your device comes up with launcher app, and you can install Nova launcher app from play store. When such similar apps installed, you need to set a default app for use. to do that, go to Settings->Apps->Default apps->home app. set the one you required. It will also asks you to set default launcher while pressing home button after installation. 


system apps has options in settings: DISABLE and FORCE STOP 
user apps has options in settings :UNINSTALL and FORCE STOP 


DISABLE is used disable app function. App icon will be removed from launcher. it will not affect other apps. Also, you cannot disable every system app. 
FORCESTOP to stop currently running app
UNINSTALL remove app from device.