What's the difference between OS updates and OS upgrades?
Updates:
Let's presume your computer came with Mac OS 10.15 (Catalina) and is capable of running the latest OS, which at the moment is OS 13 (Ventura).
Updates will normally contain bug fixes and or security fixes. So if you applied all the updates to Catalina it will now be running 10.15.7 i.e there has been seven updates.
Upgrades:
The computer is now running 10.15.7, and you've been offered an upgrade to Ventura, there are things you need to check before doing any upgrade.
The main thing is third party software, check that it will run with the OS you're going to upgrade to its too might need upgrading. Also check your printers, scanners, MIDI interfaces etc. they may need the drivers updating to run with the new OS.
Summary:
Updates should be applied to keep your installed OS secure.
Upgrades should only be applied if you're sure all your equipment and software will run.
Tip:
When any updates are offered, wait a week or so before applying them. Sometimes the update itself needs an immediate updating because it's stopped something from working, i.e printing, connection to server etc.
Upgrades, best waiting for at least one update. The first version always seems to have the most bugs.
Please wait... it will take a second!