Xbox has no freakin' games!

[blublibla]

The Xbox 360 is one year older and more tired than the PS3.

So it's normal that it's both selling less consoles, and having less exclusive releases.

Also it's a matter of talent and legacy: Sony has been around for 4 generations with one of the most iconic console (the Playstation) then the PS2, and most of its developper studios emerged from then (Naughty Dog, Quantic Dream, Santa Monica...) while the first Xbox already had few worthy exlusives to follow-up on the Xbox 360, which didn't have as much worthy IPs as the PS3 did either.     

So in fact, if the initial appeal of the PS4 is already stronger than the Xbox One, and more remarkable exclusives are releases first on the PS4, other developper will probably follow and focus on the PS4 making it the future success.