Kinect Sports Rivals uses Kinect to capture the player's likeness and use that in-game instead of an Xbox Live avatar. It's just one of a number of new features Rare has developed using the grunt of Xbox one and the new Kinect sensor.
According to Microsoft, the use of new tech means "skill matters", "precision is rewarded", and "small movements make big impacts", which is a far cry from the failathon of most motion games to date. This talk of precision is important because Rare is championing the mini-games collection as a competitive experience with online tournaments - hence the subtitle.
Initially expected as an Xbox One launch title, Kinect Sports Rivals has been delayed to northern autumn 2014. It's Rare's first Xbox One title, not to mention likely to become a showcase for the new Kienct, so Microsoft's delay for further polishing seems like a solid move.