The difference between Pony and Rust is that Pony allows easy reference cycle.

One of the innovative point of Pony is the iso reference. iso reference means that an object graph is accessible from only that iso reference. It avoids sharing mutable data.

And that it has a nice garbage collector, which is good enough due to the way capabilities work, being per actor, and how references work.

Pony also seems to hide more complexity and come with more batteries included than Rust, making it a little closer to the spirit of Go in that sense. That’s my first impression.