A rinse is much thinner than a conditioner, and is usually more for detangling. Dominicans will often condition w/ one product and comb a rinse through after that (at least the salons that I've been to). I think the main difference is that a conditioner contains ingredients that are supposed to do something to the hair, i.e. add protein, moisture, shine, nourish split ends, add volume, etc., and a rinse is just supposed to make the hair more combable after shampoo. Just my .02 cents though. HTH