You can use the regular data structures in java and run into issues with concurrency but you can also use unsafe in rust so it’s a bit of a moot point.

In Java it isn’t always clear when something crosses a thread boundary and when it doesn’t. In Rust, it is very explicit when you’re opting into using unsafe, so I think that’s a very clear distinction.

Java provides classes for thread safe programming, but the language isn’t thread safe. Just like C++ provides containers for improved memory safety, and yet the language isn’t memory safe.

The distinction lies between what’s available in the standard library, and what the language enforces.