React is not the same as React Native... there's enough similarities to share a name. React is the base (afaik) for all web-based client interactions, which also includes a lot of TV/Webtop interfaces, but not necessarily Android and iOS.

Given the shift towards Flux and Falcore, React Native may make sense for the iOS/Android, and potentially in Windows/Ubuntu as well (speculating).

Disclaimer, I don't work there, but did go through the interview process last year, I wasn't enthusiastic about moving to California at the time.

No worries! Tracker1 is correct that all browser based UI is built using React. Other platforms may be doing their own explorations into React but I can't speak to that since those are outside of my domain of expertise. I can say that my team loves React so we're definitely looking into React Native.