Rigid PVC and flexible PVC are two types of polyvinyl chloride (PVC) that have different properties and uses. 

Rigid PVC is a strong, hard plastic that is commonly used in construction and manufacturing applications. It is often used to make pipes, window frames, and other structural components. Its rigid nature makes it difficult to shape and form, but it is very durable and resistant to corrosion, moisture, and chemicals. 

Flexible PVC is a softer and more pliable form of PVC that can be easily molded and shaped. It is often used in the production of hoses, tubing, and other flexible components. It is also used to make items like flooring, shower curtains, and wall coverings. Flexible PVC is more resistant to abrasion and weathering than rigid PVC, and it is also easier to work with. 

In summary, rigid PVC is a strong and durable plastic that is used to make pipes and other structural components, while flexible PVC is softer and more pliable and is used to make items like hoses, tubing, and flooring. Both types of PVC have their own advantages and disadvantages, so it is important to choose the right type of PVC for the application.