They're technically parallel universes, based on a short paragraph at the start of the book:So are they parallel universes or a different continuity/non-canon?
Buuut one must consider there already exists things outside Creation, such as the Underworld, Hell, and the Wyld. Which don't connect or interfere with any of the other shards. So in practice they're different continuities.Creation. It is a word that is a place, and a place that is a thousand more: worlds and realms changing under the shifting light, like a thousand different reflections from the shards of a broken mirror. When the mirror shatters, it reveals a mad math of worlds, a conspiracy of ideas, places, and themes that nevertheless evoke all the myth and legend of the world that came before. Do not believe what the scientists tell you.