I have just bought a new Pi4 and want to start off with Ubuntu OS rather than with Raspberry Pi OS. I wasn't sure if I should use NOOBS or Raspberry Pi installer for setting up the OS on the microSD but ended up using the Raspberry Pi installer to set up the OS anyway.
What is the difference between the two and when should I use one or the other if I want to set up an OS other than the official Raspberry Pi OS?
NOOBS is past its use-by date. It was, probably a good idea when it was introduced as you only need to be able to unzip and copy files to get a bootable SDCard.
Now there's Balena Etcher and the RPimager. Etcher will take a downloaded still zipped image file, unzip it, write it to the SDCard and verify it. RPimager does the same but also includes a menu to let you choose which image file to download.
https://www.raspberrypi.org/downloads/
RPimager runs on Windows, Linux and Mac OS.
The RPimager is your tool of choice - for plain RaspiOS it's doing the download for you. For alien OSes like Gentoo or Ubuntu it can use the zipped image file you've already downloaded. The verify function means you can be sure the SDCard isn't a fake.
