The main difference between the vests is that safety vests are designed to help a person swim if his boat (or other small vessel) capsized, and life jackets are kept afloat without the need to swim independently, including keeping a person unconscious.
Life jackets interfere with normal swimming and therefore are not suitable for rafting on local small rivers.
For example, if the ship capsizes while passing the threshold or you just swim on hot days in a life jacket, the life jacket will interfere with your return to the ship, but the safety vest will help you swim, because it will not restrict your movements.