Rust does prevent data races (as in multiple threads writing to the same memory location is explicitly forbidden by the borrow checker), but it doesn’t prevent race conditions, which is a more general family of concurrency bugs.

In short, the borrow checker allows a single owner at all times, or it allows references to the object, abiding these rules: it may have any number of read-only references (they are safe to share), OR a single read-write reference.

They couldn't be more different.

Java's synchronized keyword changes how code is interpreted to use expensive locking and data fences in order to prevent logical race conditions.

Rust's semantics do not alter the compiled code or insert any locking behavior. They prevent you from writing incorrect code to begin with.

In other words, Rust doesn't do anything magical to deal with data races at run time. It prevents you from expressing programs that have data races in the first place. It's a compile time analysis, not a run time behavior.