New FAQ added to KDE neon FAQ.
KDE neon does continuous deployment of the latest KDE software which means there are nearly always new versions of our software to update to. We recommend using Plasma Discover’s updater which appears in your panel: 
If you prefer to use the command line you can use the pkcon command:
pkcon refreshpkcon update
This will install all new packages and uses the same PackageKit code as Plasma Discover. Some uses of apt do not install new packages which makes it less suitable for KDE neon.