I think that difference is that Deno is some kind of commercial startup and Rust feels like community project backed by few huge corporations. So Deno needs to generate hype while Rust's not hurrying anywhere.
Are you familiar with the concept of no-2.0 for Rust? The do this on purpose so the users (the software engineers) never need to convert a version x project to a version y unlike for example Python (2 -> 3). I think this is amazing.
I wonder if they considered an edition like system for Deno versions. I would say that it’s likely too much upkeep for a commercial project, yet I somehow doubt that the Rust project has more capacity, whether that’s funding or engineering resources.