David, also note the the pictures are taken from differing viewpoints. The B&W photo appears to be taken from a standing position in line with the main straight. The catalog shot was taken from a higher position, probably a stepladder, and shows most of the outside wall of the straight. The donut IS different, though. It appears that the inside wall coming out from under the bridge turns, and extends up the short straight. In the catalog photo, that wall terminates much sooner.
AMCR tracks were built in jigs, and some pieces/parts were used in different designs. To my eye, the only piece that is particular to the Sovereign is the bank. It runs into a King deadman, then to a Windsor (Yellow) bank, followed by another King deadman, then another Windsor bank, and into a King 90. The donut is a King item, with the addition of two short straights. The bridge and lead-on both appear to be King track items, as well. Anybody else ever notice this?