“Single family” refers to a property designed as one dwelling space for either a single person or one family. Examples include a single-family house, a single apartment unit, a cottage, or a finished basement.
“2-4 unit property” refers to a property with 2 or more dwelling spaces or units, but no more than 4 total. Common setups for this property category include duplexes, triplexes, quadplexes, or two-family homes. The units are distinct from one another and are rented out separately, though shared entrance/exits, walls, and utility rooms may be present.
“Apartment building” refers to a property with 5 or more dwelling spaces or units. They are usually contained in one building or address and have divisions between the units. They are rented out separately and each unit is self-contained, though shared spaces like laundry rooms, mail rooms, offices, and hallways are common.