Tekken has always been closely linked to the PlayStation brand, and for many years was the flagship fighting franchise of Sony's console family.  Despite finally going multiplatform in the newest iteration in the popular franchise, it seems the the Sony version of the game still remains the more popular of the two. 

Sources suggest the PS3 version of Tekken 6 outperformed the the 360 version.  No distinct numbers were given, but we do know the PS3 version sold worse than Demon's Souls, which sold above 100K. 

The bigger story here, though, is that both Tekken SKUs together sold less than 225K(estimated between 175 and 225K).  While Tekken 6 was only available to purchase 5 days prior to the end of the month, that's still a lot less than other big name fighting franchises have done, namely Street Fighter IV, which sold over 700K in about 8 days.  Though well received critically, Tekken 6 was plagued by some netcode issues, which could have detracted from the game's commercial performance as well.

[UPDATE: Top 20 software chart has been released, showing Tekken 6 PS3 at less than 113K and Tekken 6 360 at less than 100K]