Accessory Dwelling Units (sometimes called "granny units") can include a kitchen, laundry, and garage, are limited to 1,200 square-feet in size, and can be rented separately from the main house.
Guesthouses differ from secondary units in that they cannot include a kitchen, laundry, garage, separate electrical meter, are limited to 600 square-feet in size, and cannot be rented separately from the main house.
A property is not allowed to have both a secondary dwelling unit and a guesthouse.