Forgot to mention; note the cars actually have different window arrangements and interiors.
For those that aren't Santa Fe Fans; the El Capitan was a Coach Train while the Super Chief was a Sleeper (Pullman) Train. In the later years of Santa Fe, as the number of riders dwindled, the trains were combined. However by that time the El Capitan was using Hi-Level cars. The Hi-Level cars were of course were the genesis for the Superliners.
Interestingly when I rode the City of New Orleans in 1994 it was advertised as using Superliners. In truth is was a mixed consist of Hi-Levels and Superliners, of course all had the then current Amtrak Striping.