Main Difference
The main difference between Loft and Mezzanine is that the Loft is a near-roof part of a building and Mezzanine is a intermediate floor between main floors of a building
Loft
A bunk bed loft can be an upper storey or attic in a building, directly under the roof (US usage) or just a storage space under the roof usually accessed by a ladder (British usage). A loft apartment refers to large adaptable open space, often converted for residential use (a converted loft) from some other use, often light industrial. Adding to the confusion, some converted lofts include upper open loft areas. Within certain upper loft areas exist even further lofts, which may contain loft areas of their own, and so forth.
Mezzanine
A mezzanine (; or in French, an entresol) is, strictly speaking, an intermediate floor in a building which is partly open to the double-height ceilinged floor below, or which does not extend over the whole floorspace of the building. However, the term is often used loosely for the floor above the ground floor, especially where a very high original ground floor has been split horizontally into two floors.
Mezzanines may serve a wide variety of functions. Industrial mezzanines, such as those used in warehouses, may be temporary or semi-permanent structures.
In French architecture, entresol also means a room created by partitioning that does not go up all the way to the ceiling; these were historically common in France, for example in the apartments for the nobility at the Palace of Versailles.
Loft (noun)
air, the air; the sky, the heavens.
Loft (noun)
An attic or similar space (often used for storage) in the roof of a house or other building.
Loft (noun)
The thickness of a soft object when not under pressure.
Loft (noun)
A gallery or raised apartment in a church, hall, etc.
“an organ loft”
Loft (noun)
The pitch or slope of the face of a golf club (tending to drive the ball upward).
Loft (noun)
A floor or room placed above another.
Loft (verb)
To propel high into the air.
Loft (verb)
To fly or travel through the air, as though propelled
Loft (verb)
To throw the ball erroneously through the air instead of releasing it on the lane’s surface.
Loft (adjective)
lofty; proud; haughty
Mezzanine (noun)
A secondary floor, in between the main floors of a building; entresol.
“On our way to the top floor, we stopped at the mezzanine.”
Mezzanine (noun)
A small window used to light such a secondary floor.
Mezzanine (noun)
The lowest balcony in an auditorium.
Mezzanine (noun)
Additional flooring laid over a floor to bring it up to some height or level.
Mezzanine (noun)
A floor under the stage, from which contrivances such as traps are worked.
Mezzanine (adjective)
Fulfilling an intermediate or secondary function.
“To make interconnections easier, we added a mezzanine PCB.”