Some questions about overdraw calculating

The StreamLine for G76 calculate overdraw with ($MaliCoreWarpsFragmentWarps * 16) / ($MaliCoreTilesTiles * 256), and Mali Pixels with $MaliGPUTasksFragmentTasks * 1024.

$MaliGPUTasksFragmentTasks means that the number of 32x32 pixel tasks processed by the GPU fragment queue. $MaliCoreTilesTiles means that The number of tiles processed by the shader core. And$MaliCoreWarpsFragmentWarps means the number of fragment warps created.

I want to know what the difference between these three and these. Thanks.