Not very different for the rest of the world. But things in Korea would be dramatically different. First off, as Korea would be united, people in the North would not be brainwashed. Systematic propaganda would end, and people would see the truth that the world is not what the Kim wanted them to believe. We would see people's dreams shattered, their entire worlds falling apart. Suicides. Terrorism would flourish, not in the traditional sence, but as an act of defiance. These people would panic, they would be scared. Kim's death would simbolically kill the servant inside of them. A very depressed, extremely poor and defeatist people would live here.
Unlike Nazis, North Koreans have been ruling much longer, so levels of brainwashing are much higher. It would take probably decades just to make these people believe that their beloved leader and regime is gone. Dejucheization would begin.
Once that is over, we would see younger generations take the torch. They would be much more free and would move in millions to work on the South. North would essentially be in ruins, with youth gone, and old people aging, and dying. So we would see a dramatic shift in their demographics as well.
Contact of two completely opposite cultures always means the death for the less developed one. In this case it's North Korean.
I think in at least 20 years after the fall of Kim's regime North Korea could start to catch on with their Southern counterpart.
