Polyvinyl Chloride (PVC) and polyethylene (PE) are polymers that are used for both packaging and electrical insulation. 

Polyethylene or polyethene (PE) is a popular plastic used for insulating cables, wires, bushings, and transformer components. PE has excellent insulation properties and high dielectric strength. However, Polyethylene is a good choice for packaging because it's non-toxic, food safe, and can be customized into many shapes and sizes. It's also resistant to chemicals, UV light, and moisture, and can be reused while polystyrene is a good choice for electrical insulation because it has low thermal conductivity and prevents the flow of electrical current. Since polystyrene can serve both purposes, it's a better answer compared to polyethene.