Rust doesn't have classes, and therefore doesn't have virtual classes. So it ends up being different. Dynamic dispatch is used pretty rarely in Rust.

If you want dynamic dispatch, you don't use a virtual class, you use a "trait object". Basically it's a double pointer: a (pointer to vtable, pointer to data). Technically the C++ standard (as far as I know) doesn't define the exact implementation of this stuff, but in my understanding the vtable pointer is stored with the data.

There are pros and cons to each approach.