White balance is the term used to describe how does the camera balance the temperature of the image. As the name suggests, it's balancing the camera to the right temperature of color so that white is white.

Per my understanding the difference is that auto white balance makes the automatic adjusting of white balance only once at a time, for example only, when camera is powered on (and a blank white card is put in front of it).

While auto tracking white balance function provides continuous real-time monitoring and adjusting of white balance in real-time as lighting conditions change (for instance day exterior changes to tungsten exterior).

it depends on the light conditions

White Balance - 2011 was released on:

USA: 28 April 2011

because you cant mix two colors and get white, or get white from any other colors