Being better equipped and better trained didn't save the Nazis on the Eastern Front from the numerically superior Red Army. True the Soviet winters contributed, but the Red Army was able to push them not only out of the USSR but all the way back to Berlin. The Germans' 70 ton tanks, rocket planes, jet planes, ballistic missiles, and cruise missiles didn't save them either.
As for Vietnam, the NVA and the Viet Cong lost a lot more men than the US did. The decisive edge they had was morale. And the home field advantage.
Yeah but think of it this way. The Germans made many errors in the battle, not to mention General Rommel's defeat(which was more of a surrender if anything. Out of rations isn't very fun). If North Korea executed the mission with very little flaws, and since the soldiers are scared that they'll be killed if they don't follow the orders to the letter, North Korea would win if given the manpower and economic power of China.
Remember that missiles don't win wars, people do.
And remember that for the U.S, for many marines and soldiers, the military is a JOB. For North Korea, it's either take the enemy city or destroy the fortification or die by execution or die by enemy fire. True, many soldiers will fight for their life but that whole "Take the fortification or be killed" mentality doesn't exist. So long as the soldiers don't desert the unit, they won't be hanged for failure.
"As for Vietnam, the NVA and the Viet Cong lost a lot more men than the US did. The decisive edge they had was morale. And the home field advantage."
And fear of what the General would do to them if they fail...But then again, they don't care. The individual doesn't matter so long as the collective wins. That's why many of these brutal militaristic countries send in suicide bombers. Heck in the Korean War, even the South Koreans planted explosive charges in the spec op teams backpacks just in case they're captured. Kill yourself and kill the enemy since you're already going to die.