A home expansion is done by adding a structure at ground level. We add a room that is annexed to the existing building, either on piles or on a concrete slab or foundation. The size of the expansion depends on the zoning and other regulations of your municipality.
A floor addition is made by constructing a floor above the existing building. This involves architectural changes to the existing building, circulation in the house, and more. You can make a full floor addition, or just part of the property.