From a superficial look, I would argue xshell is all about bringing shell-ergonomics into your rust-code, while your rust program maintains its traditional form.

rust-script seems to do nothing about your general rust-code, but make it more easily accessible in a (bash) shell-like context by altering the base form of your program to be more script-like.

They seem to complement each other really, and I don’t see why one would choose one over the other, as they apparently solve different problems. One might even use both at the same time?