Rust has a few interlocking behaviors that provide its memory safety, a few of the most important are:

- The borrow checker enforces mutable XOR shared references.

- The compiler does not allow use of local variables before they're assigned to, requires structs to be completely initialized, etc..

- All the builtin datastructures perform bounds checks

- The compiler disallows deferencing raw pointers except in unsafe blocks.

There's a lot of good things to be said about modern C++, particular smart pointers. However, it's significantly less resilient to common mistakes than Rust is: https://alexgaynor.net/2019/apr/21/modern-c++-wont-save-us/