react-router contains all the common components between
react-router-dom and react-router-native.
When should you use one over the other?
If you're on the web then react-router-dom should have
everything you need as it also exports the common components
you'll need.
If you're using React Native, react-router-native should
have everything you need for the same reason.
So you'll probably never have to import anything directly
from react-router.