I know, which is why I said they have a common history and core. react and react-dom are both part of the same github project at https://github.com/facebook/react. Frequently when people are talking about React, they only mean the HTML version, not including React Native. For example, the Nerv project mentioned in this post.

While React Native makes use of the react core package, it is a separate github project http://facebook.github.io/react-native/