They are not intregated into the world economy like iran and are not as willing to talk as Iran. North Korea is more polictically isolated then Iran so it makes a diplomatic solution more difficult.
North Korea is even more isolated than Iran, keeping its citizens in what is virtually a nation sized prison. As such, there are significantly fewer barriers to radicalism and North Korea has far less to lose.
because of mor poorty it may use weapons
Despite having an incoherent and babbling government, Iran may seem like a dangerous country, but its leaders are not that stupid to use a nuclear weapon (even if they ever get one). They have a lot more to lose, unlike the N. Korea that has nothing to lose and just to make a point they may use nuclear weapons, therefore I think they're a lot more dangerous.
Irans aim to make her country technologically power and become a super power inits the region where as N Korea cleary communicates it can take nuclear actions ...where iran always tells we are developing for generating energy
more powerful