Another key distinction, I think, is that the Gray Waste creates apathy. It does this in order to steal the emotions of others, making itself fat and powerful from the spiritual essence of its victims, and as a weapon against those who would defy its evil, draining away their passion to fight back.
While the Gray Waste creates apathy, this doesn't mean that apathetic souls go to the Gray Waste. Souls travel to the Gray Waste because they are evil but not unbalanced toward Law or Chaos.
Similarly, Pandemonium creates madness, but doesn't attract the souls of all those who are mad. The mentally ill may travel elsewhere, depending on their alignments.
So my analyses are based on alignment first, and "theme" as a secondary consideration. Evil traitors commonly go to Carceri, but good-aligned traitors might not.
Thanks, this one gave me Neutral Good with a lawful leaning. Much better.