High-Density Polyethylene (HDPE): It has highly linear molecular chains with few branches, and its crystallinity can reach 70%-80%, thus exhibiting a relatively high melting point (typically 130-135°C). This structural feature endows it with high hardness, strength, and temperature resistance, making it commonly used in the production of load-bearing or durable items such as plastic bottles, pipes, and barrels.

Low-Density Polyethylene (LDPE): Its molecular chains contain numerous long branches, resulting in low crystallinity (about 40%-50%) and an even lower melting point (102-115°C). With a softer texture, it is often used in the production of cling films, agricultural films, and the like.

Ultra-High Molecular Weight Polyethylene (UHMWPE): It has an extremely high molecular weight (usually >1,000,000) and a crystallinity close to that of HDPE. Its melting point is slightly lower than that of HDPE (125-135°C), but it possesses excellent wear resistance and impact resistance, making it applicable in the manufacturing of bearings, bulletproof materials, and other products.