while existing in the same universe, many will find supreme commander 2 a completely different game. Some of the most distinct differences are economical, technological, and of course visual. one who is accustomed to the play of one will likely (and have in the past) strongly dislike the other.
this is one of the most noticed differences one will find. in the original Supreme Commander one must advance through the 3 technology levels (will a Supreme Commander/FA player please add to this) but in supreme commander 2 a new currency called research points comes into play. research points are used to purchase "blueprints" for new units, and upgrades which will be applied instantly at no cost to new and existing units (in fact, technological upgrades can REDUCE the cost of the units). for example, the UEF Rockhead tank initially has low speed, health and two direct fire cannons. with research it gains an extra cannon, anti-air, large HP boosts, training (HP and damage) and a personal shield at no (direct) mass or energy cost. the Rockhead is the only UEF (direct fire) non-experimental tank in the game.
in SupCom1/FA you require storages to keep your energy or mass, or else the collected resources are wasted, whereas in SupCom2 there is no limit to the resources you can collect. where the mass and energy goes is largely unknown. also in SupCom1/FA all active units require energy to function, but in SupCom2 all units are self sufficient. it could be that they all have internal energy generators of some sort, suggested by the fact that factories have a small energy output (1).