I made this illustration and used a circle for better visualization of what I mean. Basically you define the Min and Max values in the range (which end up being the same point) and the max possible difference between the 2 points is never more than half the Max of the range - so, in this case where it's from 0 to 1, the maximum possible difference between 2 points there is 0.5, because they can go back if it's closer - ... and then you define the 2 points, A and B, which you want to get the difference of.
I appreciate very much any help given!