So there are three ways to upgrade KDE Neon:

(1) Discover

(2)

Code: Select all

sudo pkcon refresh && sudo pkcon update

(3)

Code: Select all

sudo apt update && sudo apt full-upgrade

except for snaps and flatpaks, are all these three methods 100% identical ? any differences ?

When you upgrade using Discover, it uses the command in (3) + additional commands for snaps ?
When you upgrade using (2), it uses the command in (3) + additional commands for snaps ?
When you upgrade using (3), it uses the command in (3) only ?

Is there a down side in using Discover ? does it leave any residues ?

what is the preferred way of upgrading ?

According to the official KDE neon website FAQ the preferred way is with pkcon commands. According to the info there the apt or apt-get commands could fail to pull all packages necessary.