Full-time senior missionaries: Full-time senior missionaries live away from home and are temple worthy, called by the prophet, and set apart by their stake president. Missions typically last 6 to 23 months.
Church-service missionaries: Church-service missionaries live at home and serve eight to forty hours per week in a work-related assignment for a Church department. Missionaries serve for a 6 to 24 months and are temple worthy, called by their stake president, and set apart by their bishop.
Long-term volunteer: Long-term volunteers are not missionaries and are not called, set apart, or required to be a Church member. Volunteers typically serve fewer than eight hours per week for 6 to 24 months.