Loft in US usually means a higher than main floor space, often an open or half walled sleeping space. A loft could be an entire flat/apartment, or a higher space in the flat near the roof meant for sleeping. "Main floor" usually meaning street level or ground floor.......lofts are usually found in converted warehouses (in large cities) or in log cabins in the woods.

In the latter case, they are usually half floors.....a one room place with a foot ladder to the loft/half floor. The entire room has a Cathedral ceiling with a half floor covering half the floor (which is actually Air) space. A railing is required for these. Clear as mud?