What is the difference between immersion suit & thermal protective aids (TPA)?

Immersion suit
Immersion suit is a protective suit which reduces the body   heat loss of a person wearing it in cold water. Thermal protective aid is a bag with low thermal conductance, reduces both the convective and evaporative heat loss from the wearer’s body
suit made of non- flammable &  waterproof material suit made of waterproof material
Allows swimming & climbing up the ladder Can’t swim or climb wearing it
Can be buoyant & used as lifejacket It’s  not buoyant