制度 (zhìdù) refers to a system of rules, policies, or institutions that structure society, government, or an organization (e.g., political, economic, legal systems). It is broader than 体制 (tǐxì), which focuses on the institutional/organizational framework, and more abstract than 机构 (jīgòu), which is a concrete organization or agency. 秩序 (zhìxù) means 'order' as a state of stability, not a system itself.