IIRC, the top one is the first result of Garand's adapting his original machine rifle to a semi-auto Infantry rifle, the reason he was hired by SA. It's promer-actuated, a novel principle that was in contention until about 1926. The advent of crimped-in primers to reduce jamming in machine guns and other deficiencies killed it. At that point Garand had nothing and the Pederson rifle was being recommended for adoption by the testing board. It sure looked like our first semi-suto would be "The M1Pederson."