What is the difference between waterproof breathable membrane and vapor barrier membrane?

Rainwater outside enters the insulation layer. However, the vapor barrier film is a protective film used as a vapor barrier layer. This protective film is usually under the thermal insulation layer. One acts on the top of the insulation layer, and the other acts on the bottom of the insulation layer, so the methods of action are different.
The basic functions are different: the main function of the waterproof and breathable membrane is to prevent rainwater from entering the insulation layer, and it can also discharge some moisture generated in the insulation layer to the outside, keeping the insulation layer dry for a long time. However, the waterproof and breathable membrane functions as a moisture-proof and vapor-proof membrane, which can effectively prevent indoor moisture from penetrating into the insulation layer.
The basic impacts are different: the waterproof and breathable membrane has a strong protective effect on the insulation layer, so it will not affect the service life of the insulation layer. However, the insulation effect of the vapor barrier film is different, which will affect the service life of the insulation layer.