[browniefed]

react-navigation will supersede all existing navigator solutions in React Native core (Navigator/NavigationExperimental).

React Router v4 is building a react-native integration to show that it is capable of working on Native. It's centered around URLs so it's attempting to make Deep Linking into your application easier, as well potentially re-using the same navigation on the web.

That being said react-navigation can do both of those things as well and is fully supported by react-native core contributors.

[mxstbr]

Out of curiosity, why was the decision made to build a completely new router (react-navigation) vs collaborating on better native support to the existing react-router? (which is working towards that anyway)

[browniefed]

Difference in opinions about what could be accomplished via react-router vs what native paradigms needed to be crafted.