Flywheel differences early to late style single mass, Carbureted vs Montronic?

[coupe2800cs]

Got couple flywheels here, one I got from someone that parted out a E12 or supposedly, and and the other one came off an engine pre 1980 E23 M30 B32. The one that came off the E12 has visually less material around the outside edge near the ring gear, while the later M30 one appears to have little bit more meat on the outer edge near the ring gear. Assuming one is used for carbureted cars vs Montronic cars ? The rusty looking one is image pulled off EBay for comparison, my actual flywheel is at the the machine shop…