No, I think you're just confusing the terms a bit. You are still free to create an instance of the enclosing class within a top-level nested class, but, with an inner class, you must have an instance of the enclosing class before you can create an instance of the inner class.
As an instance of the enclosing class must be created prior to the instance of the inner class, all true inner classes have an implicit reference to the instance of the enclosing class. Therefore, you can use a modified version of the keyword this, like this, to access members of the enclosing context:
That implicit reference to the enclosing instance doesn't exist in a top-level nested class because the class can be instantiated without an instance of the enclosing class, like this:
As you can see, I didn't need to make an instance of the class
Test prior to instantiating the class TopLevelNested. I was required to do so in the previous example.
I hope that helps,
Corey