Different colors count food differently. Some plans have more foods that are zero points and give you less points to use on other things. I am on green which is the strictest. It has the most points though. I am not 100%, but I believe purple has the most zero point foods and the fewest other points. It allows you to eat from a list of foods without measuring and worrying so much about portion sizes. You need to be able to listen to your hunger signals though and eat to fullness and not overeat.