One is a major difference their types of government. The South is a democratic state while the north is a totalitarian Communist state. They have diffrent laws as one permits personal freedoms while the other restricts any freedom once so ever. They do share one thing though their people and language and resoundingly that is about it. The only reason for them to agree is that their people just want resolve but truly the only people caring for this is the south and the northern higher ups. If the North can get on the political stage and heck get political legitimacy that would be the ultimate reason for them to formally end. The reason for the south to is to reach a resolve. Here the north can only gain and the South well only increase moral of the people and very little at most. Lets be clear though the North is in no way shape or form going to attack the South and even if it did it would not win. If the country barely has the capacity to feed it's people I doubt it would have any reason to attack the South. Even if it did China in it's own decline econmomically would find it hard on the world stage to ever support the North as it would put them in political and ecomomic ruins even further. So in this case the North would be incapable of winning unless China did a 1953 which could lead to a world war but that's extremy unlikely. The US could help since it was a defensive war. But let's be honest any offensive war gains any support and when it does it gets very little on the long term.