A duplex is a home on two floors connected by an internal staircase, which can be anywhere in a building. A penthouse is a home on the top floor, usually with a private terrace and often larger and more expensive than the floors below. A top-floor duplex can be both.
Side by side
Factor
Duplex
Penthouse
Defined by
Two levels with an internal staircase
Top-floor position
Location in the building
Any floor, or a house
Top floor
Private terrace
Sometimes
Usually
Price
Varies
Usually the highest in the building
Exposure to heat and leaks
Depends on floor
Higher at the top; check waterproofing
Terrace area in carpet area
Exclusive terrace excluded under RERA
Exclusive terrace excluded under RERA
When Duplex matters
A duplex suits buyers who want separate living and sleeping levels.
When Penthouse matters
A penthouse suits buyers who want views, a private terrace and privacy, and can manage the upkeep of a roof-top home.
In more detail
Exclusive open terraces are not part of carpet area under RERA; they should be stated separately. Check whether you pay for the terrace and at what rate.
Confirm the terrace is shown as exclusive in the approved plan and the agreement; a terrace that is a common area belongs to all owners.
Common questions
Can a penthouse be a duplex?
Yes. A top-floor home on two levels is both.
Is the penthouse terrace part of carpet area?
Not under the RERA definition. It should be stated separately.
Are duplex flats more expensive?
Not necessarily per square foot; it depends on the project and floor.