"Memory safety" is referring to safety from null-pointer dereferences, use-after-frees, buffer overflows, data races, invalid pointer casts, etc.
Safe Rust has no undefined behavior. Memory leaks are bad but they don't cause undefined behavior (your program might use more memory than it needs, but an attacker can't gain remote code execution from a memory leak). So Rust has tools (such as RAII) to help prevent accidental memory leaks, but it doesn't guarantee absolute freedom from memory leaks.
Safe Rust has no undefined behavior. Memory leaks are bad but they don't cause undefined behavior (your program might use more memory than it needs, but an attacker can't gain remote code execution from a memory leak). So Rust has tools (such as RAII) to help prevent accidental memory leaks, but it doesn't guarantee absolute freedom from memory leaks.