The Allies, which are Britain and the US in the game, the Russians are seen as a seperate power, and ofcourse the Germans. Each side has engineer trucks, transport trucks, medical trucks as additional vehichles. All 3 sides have diffirent types of infantry, depending on the army, there can be snipers, machine gunners and officers. Machine gunners come in various sorts, which you'll notice while playing the game. Some infantry units are also equipted with grenades, some with rocket launchers and not to forget, the german panzerfaust.
Infantry can also arm artillery, heavy machineguns and mortars.
They also control the Anti Aircraft guns. They play a highly strategic role during the missions in which they are available. Spy planes can clear the fog of a specified area for some time, while B17 bombers drop huge bombloads on the enemy. Than there are paratroopers, nothing more beautyfull than seeing loads of these little chutes flow down behind enemy lines. The Russians also come with the famous Katyusha rocket launchers, and they can attack from long range with a high firing rate.