I am not a Zorin OS Developer.
sudo apt update && sudo apt upgrade
This includes snaps or flatpaks.
Some packages that are installed as .deb packages or as applets will not upgrade through the above. Those must be manually upgraded by reinstalling the latest .deb.
The user is responsible to know what they have installed and upgrade accordingly.
In the last few days on the forum; one thing made very apparent in troubleshooting as of late is the Use of GUI inhibits the users from knowing their packages.
A user removed a package using Software store and it also removed the dependency of the Zorin Desktop along with it. It gave him no warning; The terminal would have printed the warning and asked a confirmation before proceeding.
A user installed a package, felt it did not suit his needs and removed it using Software store. He has no idea what packages were installed, what was removed and what information to relay. We have no idea, since he has no idea. We do not know what went wrong with his system or how to help him - clues to follow are meager at best.
In using the terminal, all affected packages are printed on the screen. All removals are printed on the screen. All installations are printed on the screen.
GUI is fine. When it works.
Terminal is fine. When it works.
When GUI doesn't work; it is a major problem.
When terminal doesn't work - it tells you what went wrong and often - how to fix it.
There is no official way to update the system; but there are effective ways to safely update and monitor. With Linux; the power to do so is restored to the user. Use The Power.
No, either method of upgrading and updating provide the same security. However, you may get updates slower if you have automatic updates disabled or run updates infrequently.