electoral system; voting system
Refers to the set of rules governing how elections are conducted and how votes are translated into seats.
Japan's electoral system is a parallel system combining single-seat constituencies and proportional representation.
Reform of the electoral system is being discussed.
選挙 means 'election' in general, while 選挙制度 specifically refers to the institutional framework or system of elections.
制度 means 'system' or 'institution' broadly; 選挙制度 narrows it to the electoral context.
Compound of 選挙 (せんきょ, 'election') and 制度 (せいど, 'system').