Static memory safety is a spectrum and so is code quality.

> how is that different from C?

Zig gives you far more memory and type safety than C and without a borrow checker and a complex generics system.

Zig also allows optional runtime checks (at the cost of runtime performance).

There is no better language between Rust and Zig because they have different tradeoffs that are better or worse in different scenarios. It is more like Rust vs C++ and Zig vs C.