The differences are the amount or the concentration of oils that are in the scents. The higher the concentration of oils, the longer your scent will last, and the less you should need to apply. Are all of your products genuine?.
Malibu Sun Lotion Bundle SPF 20 with After Sun Sun Lotion and Sun Cream
2 x Malibu Sun Lotion SPF 10 Low Protection Water Resistant 200ml
2 x Malibu Sun Lotion SPF 6 Low Protection Water Resistant 200ml
3 x Malibu Sun Lotion SPF 30 Medium Protection Water Resistant 200ml
3 x Malibu Sun Lotion SPF 15 Medium Protection Water Resistant 200ml
3 x Malibu Sun Lotion SPF 6 Low Protection Water Resistant 200ml