Maybe I am wrong or my understanding is oversimplified. But the way I understand it is that when you add a dependency to your cargo.toml file, when you run the build rust is going to cargo and downloading those dependencies you added for you and stores the dependencies with project files.

Then when you rebuild it is checking cargo to see if there is a later version and will update according to how you specified the version in the cargo.toml file.

So you are using cargo. it’s basically just automated, so you don’t have to manually interact with cargo the same way you do with pip.