What Is the Difference Between High Impact Polystyrene and Regular Polystyrene?

If you pick up the outer casing of a household refrigerator and knock on it, it flexes slightly instead of cracking. Now look at the clear yoghurt pot in the same fridge; if you tap it, it feels rigid and brittle compared to the other one. Both are made from polystyrene, but they behave differently. […]