Swim vests provide less buoyancy than life jackets and are intended to help children gain confidence in the water while learning to swim. Life jackets are designed to keep a person's head above water and prevent drowning. 2. Swim vests are usually made of lightweight, flexible materials and have an adjustable strap or buckle for a secure fit. Life jackets may be bulkier and have more straps or buckles. 3. Swim vests may be appropriate for children who are learning to swim but are not a substitute for adult supervision. Life jackets are recommended for children who cannot swim on their own or who are not strong swimmers.