In the England and Wales, some flat owners own shares in the company that owns the freehold of the building as well as holding the flat under a lease.
This arrangement is commonly known as a "share of freehold" flat.
In some parts of the world, the word apartment refers to a new purpose-built self-contained residential unit in a building, whereas the word flat means a converted self-contained unit in an older building.
An industrial, warehouse, or commercial space converted to an apartment is commonly called a loft, although some modern lofts are built by design.
An apartment consisting of the top floor of a high-rise apartment building can be called a penthouse.
In the United States, some apartment-dwellers own their units, either as co-ops, in which the residents own shares of a corporation that owns the building or development; or in condominiums, whose residents own their apartments and share ownership of the public spaces.
Most apartments are in buildings designed for the purpose, but large older houses are sometimes divided into apartments.
In Malaysian English, flat often denotes a housing block of 2 rooms with walk-up, no lift, without facilities, typically 5 storeys tall, and with outdoor parking space, while apartment is more generic and may also include luxury condominiums.