Manufacturers also called their 2 door post model sedans when the 2 door model used the roof of the 4 door sedan. Some companies used a different name for their 2 door sedans based on the 4 door sedan, though, such as Hudson who called them 2 door broughams.
Coupes originally used a greenhouse smaller than the sedans, giving a close-coupled look to the design and less rear legroom inside the car. Two door sedans that were marketed as 2 door coupes starting in the 1960's generally either used the 2 door hardtop body with a fixed quarter window and no window frames on the doors (1968 Plymouth Roadrunner 2 door coupe) or used a body with smaller greenhouse (1960-64 Chevrolet Corvair 2 door coupe)