There's no difference between them except the colours ! They're all used in exactly the same way.

Begin by applying your soap or facial cleanser, depending on where you want to use the scrub stone. Then gently rub the scrub stone over your skin with light circular movements.

You are strongly advised not to use it on very sensitive areas, such as the neck or eye area.

You can use the scrub stone on any part of the body and on the face, but you should avoid using it on sensitive areas such as the neck and eye area.  

Yes, it can!

It actually has a natural healing effect, so you can use it on spots (acne or blackheads), itchy areas and mosquito bites. It also helps to get rid of bad smells (sweat, garlic on your hands after cooking, etc.). And last but not least, it can smooth calluses and rough, dry skin on the heels, elbows, knees, hands, etc.