It's marginal. The difference exists because Function adds syntactic sugar to make the developer experience of calling the compiled functions easy and smooth. The Function call isn't a direct call; whereas the Rust one is.

It's possible to hack Function to perform a direct call and avoid (most of) the overhead, but in 99.99% of use cases this won't matter cos most processing time will be spent in the body of the function, not the scaffolding that Function uses.