Polypropylene vs PolyethyleneWe get asked, which is better, polypropylene or polyethylene. It is not a matter of better- it's more a matter of- what is your application? What are you trying to do? Both plastics are considered commodity plastics. These are plastics that are used in high volume for a wide range of application. Plastics that compose commodity plastic are polystyrene, polyvinyl chloride. poly(methl methacrylate), polyethylene and polypropylene. A step up from commodity plastics are engineered plastics which are specialized plastics that are more expensive and are used for low-volume applications.