What is the difference between Nioxin systems 1 and 2? System Kit 1 is designed for natural, non-colored hair with light thinning. It is formulated to amplify texture and protect the hair against breakage. It also refreshes the scalp and delivers thicker, fuller hair. System Kit 2 is formulated for natural, non-colored hair with progressed thinning. It delivers thicker, fuller hair, while protecting every hair strand against damage. Contains UV protection ingredients.