POT (Profit on Turnover) is Long Term say over a year

ROI (Return on investment ) is a Daily thing.

POT You have a bank of $5000 which you have turned over once in the year for a profit of $880 (Bank now $5880)

Formula $880 Divided by 5000 % = POT for the year of 17.6 %
So for every $100 outlaid you made a profit of $17.60.

Most Professionals would kill for this figure but this is only a example

Hope that helps.