It is not really a secret that PlayStation 4 has been consistently outselling Xbox One by a wide margin since both consoles were released. In order to hide this fact, Microsoft stopped releasing Xbox One sales numbers months ago and replaced them with selective and ambiguous statistics.
Selective data aside, the latest independent market report estimates that Xbox One barely sold half as much units as the PlayStation 4 did worldwide. The report, prepared by Super Data, puts the total number of PlayStation 4 sold worldwide at 55 million units while it estimates Xbox One to have sold a - relatively - meager 26 million units so far.
Interestingly enough, this 2-to-1 ratio seems to have been nearly constant since both consoles were released in November 2013.