There is a difference between these two types of lines and how they interact with water. Polyethylene is a very strong and durable material that can be found in several different types of lines, braided or monofilament. Many monofilament lines have a core than nylon covering. The nylon is hydrophobic so it can cut through water quickly and efficiently. Either one is a great choice and for surf fishing, the polyethylene may be a bit more durable for the initial shock of a big fish.