There are more differences. Packages can release updates arbitrarily, while standard libraries tend to have longer release cadences. It's also more difficult

There are more differences. Packages can release updates arbitrarily, while standard libraries tend to have longer release cadences. It's also more difficult to put arbitrary code into an stdlib, because stdlibs are scrutinized better. Also, it's harder for some random anonymous developer to gain push access to stdlib repository. One of the reasons so much Rust code is in libraries is not because there are no people to write it (duh), but because putting these in std commits maintainers to keeping backwards compatibility and slows down included package's release cycle.