That document is outdated and was written with an Akka-centric view. The author from Akka's side of things, Roland Kuhn, has since moved on to Actyx, from what I can tell.

The doc predates ACID transactions support in Orleans, but it talks about the Virtual Actor model vs the Akka model in general.

There's also Akka.NET which is probably a better comparison: https://getakka.net/