Is there any difference between nested sealed sub-classes and not nested sub-classes except for the way sub-classes are accessed?

AFAIK there is no difference. Historically sealed subclasses were only allowed when nested. This limitation was later removed to allow subclasses to be defined in the same file, for convenience.

Non-nested interact differently with the parent class’s init block, but I can’t remember the details. All I know is weeks ago I was getting some error regarding accessing parent

init

for non-nested, but when I made it a nested sealed class instead, the error went away.

@kyleg That's a rather strange behavior. Would you mind sharing the code that failed ? It may be a bug.

I don’t think I can. I ran into this weeks ago and definitely have refactored since. I think I was trying to do some sealed class stuff related to JB Exposed tables or entities.