One you use to manipulate the system / solve problem efficiently, vs. creating GUIs. Which has heavy repercussions on what types of developers use it, how the ecosystem and language is built. One metric to distinguish them is new features / year; admin + hacker types want a stable & clever interface, companies and UI devs new features. And yeah, Rust is a bit of both of them, but has all the characteristics of the later.

I have the feeling, you soon need a meta-language or extensive IDE-help to even use it. Just like C++.

edit: In hindsight, this sounds more silly than i thought. There was a great article about it i can't find anymore, with the conclusion, that Rust is no systems language by that metric.