Most English localizations, such as "American" or "Australian," have sub-variants simply titled "Variant 0" or "Variant 1."
What are these sub-variants? How do I view them?

Menu found under System Preferences, Personalization, Regional Settings, Spell Check.
Running KDE Neon 5.17 User Edition, first time with KDE, but long-time Gnome2/MATE user. Thank You!

Two easy ways to find out: try it or read up https://en.wikipedia.org/wiki/Keyboard_layout

Mamarok wrote:Two easy ways to find out: try it or read up https://en.wikipedia.org/wiki/Keyboard_layout

I did try the different variants, but saw no change. I tried spelling a few words, like "color" and "colour" to see if I could find any change in spelling rules. So far, I coudn't find a difference.

It is a nice article on physical keyboard layouts, like "QWERTY" versus "Dvorak," and so on, although little on the Spell Check question. I'm thinking the Spell Check variants might be related to things like "through" versus "thru," or "localization" versus "localisation," and so on. I'm just having trouble finding that documentation/reference, or actual changes in Spell Check utility.

Thank You, Mamarok.

Oops, my bad. Spell check can vary depending on which standard spelling libraries you use, hunspell or aspell are two that come to mind. Maybe the variation depends on those?
I know there are many differences in German for instance, depending on whether you use new or old grammar rules (for standard German), which do not all apply to the German (Switzerland) variant, so you basically end up with many differences, and hunspell and aspell provide different packages.
Another possibility is that there are two libraries provided from different sources (most often different universities that compiled the library), this can also end up being a variant. Unlike Libreoffice neither hunspell nor aspell do provide much details on this in the packages, but I am sure it can be found on their documentation.

Understand that we do not provide the spelling libraries, we only provide translations to the distributions.