Hi @aryam, thanks for your query. The GazeDirection is a direction vector telling us where the user is looking, which you can get both in World and Local space. For example, the value of (x=0, y=0, z=1) in local space tells us the user is looking straight ahead.
If you wish to compare the difference between two samples, we suggest you to calculate the delta between two frames, for example:
var deltaAngle = Vector3.Angle(previousGazeDirection, currentGazeDirection);
Hopefully this makes sense to you, please let us know how you get on. Best Wishes.