Only superficially. You cannot specify a past version of Rust where features existed that have since been removed by doing that. You also do not have a situation where two different incompatible languages are being accepted by the same compiler and as long as you specify which one is used, the compiler will properly compile code for it. For example, C will not accept headers with C++ exclusive features like namespaces and C++ will not accept headers with C exclusive features like variably modified types.

The only reason you see people grouping the two languages together is due to history. They are both derivatives of an ancient prestandard form of C called K&R C. They both have different standards committees who had different ideas about how to move forward from K&R C. The result is that C compilers were extended to support both, and that extension continues to this day despite the divergence between the two languages. The C standards committee accepted some of the changes the C++ committee made to K&R C, although the C++ standards committee does not reciprocate by accepting changes made by the C standards committee. This is making them increasingly different languages.

Try to spend time learning how other things work instead of posting replies that attempt to reinterpret everything people tell you through a Rust lens whenever someone is kind enough to answer your questions like you are doing here. It is like asking people how Chinese works and then telling them “English does it this way”. The “nothing matters but <insert language here>” mentality that causes that is going to annoy a large number of people from whom you would otherwise be able to learn.