A Type C Spain visa is a short-stay Schengen visa allowing you to stay for up to 90 days within a 180-day period. It is used for tourism, family visits, or business trips. A Type D visa is a National Long-Stay Visa that allows you to stay in Spain for more than 90 days, up to one year. Type D is used for purposes like work, study, or family reunification, not for tourism.