A Type C visa is a short-stay Schengen visa for stays of up to 90 days within a 180-day period, suitable for tourism, family visits, or short-term travel. A Type D visa is Estonia's national long-stay visa, designed for those who need to remain in the country for more than 90 days, with stays of up to 365 days permitted within 12 consecutive months. While both allow limited travel within the Schengen Area, the Type D visa falls under Estonian national immigration law and has different eligibility and documentation requirements compared to the Schengen visa.