Each of these supply the tested and vetted Nvidia Drivers for use on GnuLinux.
The primary difference in your list is the Source - which will create variance on which drivers are included. Some sources seek later Nvidia drivers than others do, as those others seek the most stable Nvidia drivers to provide.
The First sourced option is the base Zorin OS repo.
The second is the Canonical Ubuntu teams Stable Nvidia graphics drivers and patches.
The third is cutting edge drivers.
These are what are supplied by Nvidia directly - but may not be optimized for GnuLinux or Debian/Ubuntu/Zorin OS.
They are optimized for Windows OS.
I usually do not recommend this route except in cases of dire need... It's not worth the headaches.
I ask because when installing Zorin there is an option to select proprietary software or not. If someone didn't say yes there, would the Nvidia drivers still be displayed at Software&Updates>Additional drivers?
If you do not select that, then you will get the Open Source Nouveau Driver, not the proprietary Nvidia driver.
But would jockey still offer and display the Proprietary drivers? I am not sure... I have never tested this.
I would think that it would - and that the selection made during install was in regards to which driver gets installed, not to the choice in sources.
As long as you are set to Main Server, (which you are) you are good on Zorin software is concerned. Regarding Nvidia, all you need be concerned with, is additional drivers...
Regardless of which driver version you choose, just make sure you choose proprietary, not server, not open kernel. Proprietary unlocks all features of your Nvidia GPU, so long as Nvidia's driver has unlocked them on Linux, like Ray Tracing, or HDR for example.
BTW, I think Zorin OS 18 is supposed to support HDR I heard, due to modern support, I sure hope so.
If you have added a different ppa for the Nvidia drivers, do you also select the drivers via the GUI in Additional drivers or do you have to install them via the terminal? Are the commands the same as otherwise without ppa?
Will the drivers that the ppa offers always be installed or can you choose between the Zorin versions and the ppa versions?
Is the exact driver version within a specific driver displayed anywhere?
Jockey application will show them in Additional Drivers tab, if you add a PPA and update your sources, either in terminal or in the Software & Updates GUI.
This cannot be meaningfully answered without knowing which commands you are referring to.
You can choose which driver to install and use either in the terminal or in the Additional Drivers Tab of the GUI.
I meant is there a way to see the exact driver version that will be installed before the installation, e.g. to compare which driver versions contain Zorin and which contain a specific ppa?
How can I distinguish in the displayed list where the drivers come from? Which are the ones from Zorin and which are others? Or will the ppa block the Zorin source?
Sorry for all the questions. I can't really imagine what a ppa is and does.
The different PPA's will carry different initial version numbers. For example 575 or 580.
So even if you do not see whether it is 580.0.19 or 580.1.02... If you see the 580 in both PPA's, they are pretty much going to be the same exact version due to their sources also being the same patching.
The PPA will not block Zorins PPA; as these are your sources, all offerings will be offered.
You can use apt-cache policy followed by the package name to determine the source.
Generally, yes.
The ubuntu-graphics PPA is all most users need. The high end gamers will want to go for other PPA's. OR those who have hardware requirements like Nvidia 4000 series and up cards.
Open is part of mainline kernel and included int he Universe Repo, not in the Ubuntu-Graphics team repos.
The Nvidia-Open is Nouveau.
This is what users see when their system falls back to llvmpipe.