Development goals
Nuclear weapons: Development of a weapon designed to destroy and kill.
Superintelligence: The goal is not to develop a weapon. Instead, every step toward it is positive, bringing great benefits to humanity. However, such a development could get out of control. If such a system reaches a certain level, it could keep improving itself and become far superior to us in a short time.
Control
Nuclear weapons: With the development result, man retained control. So far, humans have decided whether to use nuclear weapons or not to use nuclear weapons.
Superintelligence: If sometime the development of a superintelligence is reached, humans will lose the control over this and there is then no more possibility to prevent negative effects.
Effects
Nuclear weapons: the effects are localized to one city or one region, as was the case, for example, in Hiroshima. If many nuclear weapons are used and a nuclear winter occurs, all of humanity may be affected.
Superintelligence: the effects are global, can affect all mankind.