The whole using directions for different ideas/concepts is so tiring. If you ask someone what the difference is between wanting horizontal change vs sideways change I don't think anyone would be able to give a reasonable answer.
In this case, they're also just describing the horizontal change anyways??? Anarchism already has decentralization as a core tenet, it's already about allowing pluralities. There is no one "anarchism" in the same way this article is trying to argue there is no one "degrowth".