Yes they are all part of the Platoon. 4 sections of 15. In Chain of command, they also do not split into teams. so that is just a mass of 15 men.
Late War, Americans are rather large platoons. But early war, everyone but Germany and Britain had large platoons. french ran 39-man platoons, belgians Infantry PLatoons were 63 men except for chasseurs Ardenais, who were organised into 47 man platoons.
even Italians were close to 40 men. both fucilieri and black shirt platoons that fought the french were 37 men strong. the Alpini were 47 men strong.
in 1939 period, the Japanese stationed along the Mongolian border were mostly "type A" reinforced formations, with 3x 15 man sections and a 15 man Grenade discharger section of 4 knee mortars. that also happens to be who my soviets are going to fight. so it makes a good match.
by 1941, the soviets had reduced their squads sizes to 13 men but added a 50mm mortar as part of the platoon command. so the platoon is only 4 men smaller(58 instead of 62), so they are still fairly beefy formations. by 1943ish they are down to around 31 per platoon.
criticized a recent Workbench entry, I challenged him to show that he could do better... 
