One significant difference is the will of the fighters. In Gulf War II, the vast majority of Iraq's military did not believe in their cause (protecting Saddam), whereas the vast majority of the US military did believe in our cause. Morale and "will to fight" are HUGE factors in the effectiveness of any military.
Now, let's suppose you are correct and the Federal Government, under some Leftist like Hillary, orders the US military to wage war against Americans (which I doubt will happen--see my next post). The roles will be reversed: the freedom-loving American citizens will be very determined to fight, even to the death, whereas the US soldiers will likely not be committed to killing fellow (conservative) citizens. In fact, we could probably expect a large number--perhaps an overwhelming majority--of the military forces to disobey orders or even turn on the decision makers.
I disagree, although sometimes, I think that may be the only way to restore freedom in the US. The reason this won't happen is that, while Communists achieve totalitarianism through violent revolution, the Socialists are more patient and insidious. The Socialists achieve totalitarianism by the "silent" invasion of our schools, our governments, our judiciaries, and our social institutions. They disguise their true agendas and mask their true identities. They take advantage of the ignorance, complacency, and greed of the masses to gain power and control.
Yes, there are Communist revolutionaries in America: people who would like to quickly and violently overthrow our form of government. But they are the fringe element. The more dangerous--and vastly more widespread and powerful--are the Socialists who every day are patiently chipping away at America's Constitution, sovereignty, and way of life. These are people you know: Nancy Pelosi, Barbara Lee, Maxine Waters, Henry Waxman, etc. These people are the malignant cancer that's metastasizing through the body politic. They intend to achieve totalitarian revolution--and will likely do so--without having to fire a shot.