Answer
It shows distance between grid
If you have grid price range 1-10 , arithmetic grid same as before so grid will be like 1,2,3,…..9,10 , the gaps is fixed number
While geometric is the new one, it will be like 1, 1.5, 2.25 , 3.325, 4.9 , 7.5 ,……. The gaps is percentage based