Roomette. Section. Double bedroom. Compartment. Drawing room. All these sleeping car accommodations sound alike. The 1948 brochure from the Pullman Company attempts to explain through cutaway drawings how they all differ.
Click image to download this 16.5-MB PDF of this 36-page brochure.
One accommodation missing from the booklet is the master room, which was found only on the Broadway Limited, Southern Crescent, and perhaps one or two other trains. A master room was the size of two double bedrooms and, as near as I can determine, was the only streamlined sleeping room in the U.S. that had a shower.
The staggered windows on the left end of this car are a sign of duplex roomettes. This car, built for the 1947 Empire Builder, had eight duplex roomettes, four bedrooms in the middle, and four sections (totaling eight beds) at the other end, for a total of 24 beds. The tiny windows above the main windows on the section end are for the people sleeping in the upper berths of the sections; most cars with sections did not offer this amenity.
The most-recent development in the brochure was the duplex roomette. Introduced in 1937, roomettes consisted of tiny rooms whose beds folded down, Murphy-style, parallel with the length of the car. Duplex roomettes, introduced in 1942, staggered every other roomette a foot or so above the rest. Pullman fit the beds to the lower roomettes so that they rolled out from underneath the upper roomettes, helping to squeeze 24 duplex roomettes in a car that would otherwise hold only 18 regular roomettes. Since each car, no matter how many beds it held, was served by a full-time porter, packing in a few extra beds reduced the operating cost per bed.
This cutaway drawing of a sleeping car similar to the one in the photo above shows the beds of the lower duplex roomettes, on the right side of the drawing, one underneath the upper duplex roomette and one rolled out into the lower duplex roomette. This drawing is from a brochure about the 1947 Empire Builder.