The day the factions were agreed. Two of them at launch, English names for everything a player sees, and five principles that every unit and building has had to pass since.
One shared skeleton
Both factions fill the same role slots: scout, line infantry, rifle infantry, anti-tank, light vehicle, main tank, artillery, anti-air, harvester, engineer, support, signature, and the aircraft. They build the same base skeleton: yard, power, refinery, barracks, factory, service, defences, airfield. That keeps a Command and Conquer player at home in either faction, lets one AI play both by thinking in roles rather than names, and makes balancing possible role against role.
Different answers
A reskin with other stats is not a faction. Each side gets two or three mechanics of its own that change decisions: what to build, where to fight, when to take a loss. The Consortium got shields, flying salvage drones and the orbital uplink. The League got building on the field, self-repair and salvage from wrecks. Every one of those is a general simulation feature that a later faction could reuse, not a one-off.
Few units, each clear
About fourteen units and eleven buildings per faction. No filler unit that only differs by ten percent. Each faction has its own silhouette language so it reads at a glance: the Consortium clean, smooth, hovering, light blue-white; the League blocky, patched together, on tracks and wheels, rust and hazard yellow.
And no walls, for now. The League would not waste scrap on them.
What it cost
The Consortium has no line infantry, because it does not send people to brawl. That is a hole in the skeleton, accepted on purpose. The AI has to know that a faction may leave a slot empty, which turned out to be the cheapest decision of the day and the one that will matter most if a third faction ever exists.