Seats on airplanes are called airline seats. I will be discussing the way these seats are created from scratch including the differences between car seats and airline seats
Airline seats are usually arranged in rows and are made of specific components that meet the heat release and smoke requirements, FAR 25.853(b). These specific components include, but are not limited to rubber cushions, upholstery fabric, fire blocking sheet, and plastic moldings.
An important fact about airline seats is that they are made as light as possible in all of their components. The lighter the weight, the easier that the airplane can get off ground. Since an aircraft can carry up to 850 passengers, then we want to make sure that the interior is efficient and meets the weight requirement to be a safe transport.
Airline seats are first made with an aluminum or carbon composite frame that has no bottom attached to it. The upholsterer will start their job by making the bottom out of mesh. This mesh is glued on to the frame and is expected to hold a person's total weight. A car bucket seat on the other hand has a metal grill for the bottom and the backrest where the foam will sit. Comparing these two, we can deduct that the car bucket seat is a lot heavier than an airline seat.
After the backrest layer is made, then the complete frame is inserted in the upholstery with the foam already attached to it. In other words, the upholstery sandwiches the frame. This is different from car seats because in car upholstery, the foam is first mounted onto the frame and then the sewed cover. Airline seat backrest are very easy to work with.
The bottom cushion of an airline seat is made very similar to the bottom of a car bucket set. The upholstery with the cover already on it is simply placed on top of the bottom frame and later tied and tightened. This completes the seat making. In addition to seat making armrest, and plastic moldings are necessary to make the trip as comfortable as possible. Plastic moldings are used for decorative close outs, food trays, tv mounting, and armrests. Anything that is part of the seating must meet the fire heat and smoke requirements.
Sources: Airflyby, Sciencedirect, Aviator Tips, Science Direct.