"Well, when you lower something's dimensional state past the third, it'll be sent into Limbo. If you lower it all the way to the first dimension, it'll be sent to Deep Limbo. And of course The Zeroth Dimension would result in death."
Antoinette, explaining dimensions to Mozart
in "The Puffin Gets Dizzy?"


A different realm is a location (in Conniving Puffin) which exceeds our universe. Some good examples, are Limbo, Deep Limbo, and The Zeroth Dimension. The Fourth Wall is more of a pocket universe, and doesn't quite count, but is still another realm.