There’s No Such Thing As a “Styrofoam Cup”

So says Dow Chemical, which owns the Styrofoam trademark:

Most foam cups are made out of expanded polystyrene, a type of plastic. But Styrofoam is made with extruded polystyrene, which is both better at insulation and moisture resistance, Dow says. Styrofoam is used for Dow’s branded building products, including rigid foam building insulation—but never for cups.