Better processing power.
The PlayStation 4 has better games and first-party companies. Their system made more sales than the XBONE. Also, PS4 has a better and more simplified home screen/XMB (Xross Media Bar).
PS4 is simpler to use, online game play is MUCH easier then Xbox One
Speaking from a techinical point of view the PS4 has better graphics specs (1080p on all games) meanwhile the Xbox One can only run the majority of its games at 980p. Also, the PS4 has sold millions more consoles worldwide.