While both types are widely used, there is a difference between uPVC and PVC. In fact there are several, concerning their properties, how they're made and their applications.
For the most part, both types are made from the polymer polyvinylchloride. However, those making these pipes might also blend various plasticizers into the mix to make them easier to work with. When these plasticizers are not used, the pipes are referred to as uPVC.
The difference between uPVC and PVC items and pipes also extends to the properties. Plasticizers are used in PVC pipes, and phthalates are among the most common. This, and other plasticizers, are a type of odorless and colorless ester. When put into PVC, they work to make the pipes that are produced more bendable and flexible by enhancing the overall flexibility. uPVC is free from plasticizers. uPVC is also free from BPA where PVC contains it.
The plasticizers are produced when an acid and alcohol react. Commonly used acids include phthalic anhydride and adipic acid. There are different types of alcohol, and the combination of acid and alcohol works to determine the ester that can be made and the plasticizer type.
PVC is widely used to replace older aluminum and copper pipes for irrigation systems, waste lines and pool systems. Glue can be used to fasten it, and it's generally easier to cut into pieces that ensure a proper fit.
uPVC is known for being resistant to erosion caused by chemicals. It also helps to ensure sufficient water flow due to its smoother inner walls. It's stiffer than PVC, but considered to be stronger, making it possible for it to stand up against various operating pressures and temperatures.
The handling of both types of pipe is largely similar. Certain power tools meant for cutting PVC and plastic-cutting hacksaw blades work for both types of piping. The difference between the two is associated with the size flexibility. For example, if PVC is not cut precisely, its flexibility makes it possible to still fit well. However, with uPVC, it must be cut to exact measurements, or else it will not work for the intended application. This is because it's rigid and cannot be slightly stretched to fit like PVC can be.
In construction, both types of plastic are used to create an array of piping. For example, PVC pipes that are larger might be used to help move non-potable water. Another common use is for electrical cables because PVC can offer an extra layer of insulation.
In construction, uPVC is an ideal replacement for wood in many instances. For example, it can be used to create window frames that are more durable and able to better withstand the elements compared to wood. Regular PVC is not used to create window frames. This is because uPVC will not decompose, but regular PVC might. Regular PVC is also not as weather-resistant as uPVC is. For certain heavy-duty draining and plumbing, those working on construction might also use this material instead of cast iron.