Psychopaths crave stimulation because they are spiritually dead inside. They love chaos to the extent of seeing what they can get away with, competing with each other and doing demented experiments just to see what happens. They are forever bored and restless, and so their destructive tendencies share the same psychology as a bored little kid creatively killing ants and destroying their hill. The kid doesn't hate the ants or want to control the ants or anything of the sort. The kid is just really bored and will completely forget about the ants the moment something more exciting comes along.

Narcissists desperately cling to self delusions which become increasingly fragile as more and more evidence against the delusions piles up over time. Therefore narcissists are extremely obsessive about control over everyone and everything. The self delusion is prioritized above all else, and the delusion is so fragile, that everything and everyone must support the delusion at all times in order for the narcissist to be psychologically comfortable.

Narcissists are the preferred puppet playthings of bored psychopaths. Psychopaths running a civilization will always encourage rampant narcissism in that culture so they can then just fuck with it with wild results, ie nonlinear warfare on steroids.

One of the differentiating tells between the two is that when psychopaths are totally busted or called out they tend to look smugly amused, after all this was all just a game to them to ease their dead-inside boredom. When narcissists are totally busted or called out they start slipping into psychotic rage.