Birth by Sleep Realm of Darkness = Realm of Nothingness?

I haven't played BBS yet (DON'T JUDGE ME, IT'S ON MY LIST), but I think I'm pretty well-versed in it (thank you so much, internet).
Anyway, I was recently doing some research on the KH Wiki and I saw something on the Realm of Darkness' page that caught my eye.
It said that the Ansem had called it "a realm of nothingness" when banished instead of "The Realm of Nothingness."
All of this time, I thought the Realm of Nothingness was a completely separate realm or area. There was the Realm of Light on one side, the Realm of Darkness on the other, the Realm of In Between between them, and the Realm of Nothingness was either what was left (around the realms) or a separate realm altogether.

I guess I could see why Ansem had called the RoD a realm of nothingness and it makes sense (considering it is said that you lose memory in the realm of nothingness and when Ansem was talking to Aqua in the Dark Meridian, he seemed like he had some memory loss).
Anyway, I just want some clarification.
Is the Realm of Darkness one and the same with the Realm of Nothingness?

 

Hmmm, I think they are two different things.

The real of Nothingness is... somewhere that doesn't exist, I believe. Where you

Spoiler

fight with Xemnas in KHII

is this realm. When Sora and Riku walk a little, that place bring them to another Realm, the Realm of Darkness. Where the Heartless are, where I believe the darkness is born.

EDIT:

Spoiler

Birth by Sleep is already on my list too!