And as you refine your education, if you wish, you'll learn that red sedan has a '34 style grille, whereas the '33 has a bit of a forward "swoop" to it toward the bottom and a thinner outer band. Their overall body shapes are nearly identical. As for the roadster, you'll learn that a roadster has a single seat (bench style) passenger compartment and no side glass, plus a "free standing" windshield assembly. They often had a rumble seat, which if you don't know, is under what most people think of as a trunk lid. It opens "backward" to reveal the seat. Not particularly useful in any but the best of weather. If it were a body style with a front and back seat, all under one folding top, no side windows and four doors, that would be a phaeton. A convertible, or more appropriate to the time frame, a cabriolet, has the single seat (and again a rumble seat), roll up windows and the windshield is integrated into the cowl (not detachable but for the glass and it's immediate frame being removable). If it has four doors, a front and back seat, integrated windshield and roll up windows, it's a convertible sedan.