Definition: a system window is a door/window system designed systematically, using standardised profiles and accessories and passing rigorous tests (wind, water and air tightness), balancing safety, insulation and soundproofing. Core difference: ordinary thermal-break aluminium windows are mostly single-profile assemblies with low standardisation of parts and process, while a system window is a modular system developed as a whole, with better-matched profiles, hardware and gaskets and more stable performance. System windows must pass long-term weathering tests (designed for 20+ years of service life), whereas ordinary windows focus on short-term cost and age faster.