Difference between PVC and uPVC
The material which is used in manufacturing modern windows and doors called unplasticized polyvinyl chloride, UPVC for short. This material has too many advantages over any other material in window manufacturing. It is heatproof, weather resistant and chemically stable unlike PVC.
The right name is UPVC, but some people call it PVC as a common name. They refer to UPVC as PVC in some discussion as PVC is easier to pronounce — as they execuse themselves.
Advantages of uPVC are countless. For example, it is noise proof, heat proof, and dust proof. All traits and advantages is written in a dedicated post here.