There's more to it than that. React Native has a lot of things that aren't in React/ReactDOM. The most obvious is the bridge between javascript and native code.
React Native has supporting tools like the packager which you wouldn't hear too much about in high-level comparisons. But when you compare targets like iOS, Android, and Windows, they are all using different javascript engines. There is a lot of platform-specific work that needs to happen before you can write native components.
Conversely, ReactDOM has the code to create/update DOM. ReactDOMServer outputs static HTML. What we used to call React.JS (or simply react) is now the combination of React, ReactDOM, and ReactDOMServer.
React (the "react" npm package) doesn't target anything.
React Native has supporting tools like the packager which you wouldn't hear too much about in high-level comparisons. But when you compare targets like iOS, Android, and Windows, they are all using different javascript engines. There is a lot of platform-specific work that needs to happen before you can write native components.
Conversely, ReactDOM has the code to create/update DOM. ReactDOMServer outputs static HTML. What we used to call React.JS (or simply react) is now the combination of React, ReactDOM, and ReactDOMServer.
React (the "react" npm package) doesn't target anything.