From the New York Times:
North Korean Nuclear Ability Seen to Far Outpace Iran’s
By DAVID E. SANGER and WILLIAM J. BROAD
WASHINGTON – The Obama administration has concluded that North Korea’s new plant to enrich nuclear fuel uses technology that is ”significantly more advanced” than what Iran has struggled over two decades to assemble, according to senior administration and intelligence officials.
North Korea is smaller and much poorer than Iran.
Looking at 2009 PISA test scores (p. 155-157), North Korea didn't take the test, but 26% of South Korean 15-year-olds scored in the top two ranks of math tests, the fifth best performance out of 65 regions, behind only Shanghai, Singapore, Hong Kong, and Taiwan.
Iran didn't take the test, but trying to find remotely similar countries, we see Turkey with a respectable 6%, Qatar 2%, and Jordan with under 1%. In science, 12% of South Koreans scored in the top two ranks versus 2% of Turks and vanishingly small percentages of most other Muslim countries.
Moreover, unlike North Korea, Iran lets people emigrate. A lot of smart Iranians have wound up in Southern California. My wife knows a lady who arrived from Iran a decade ago and her son then majored in physics at Caltech. Probably a better decision for the family, all in all, than staying in Iran, having the son get drafted into the nuclear program, and then having the Israelis someday drop a bomb on his head. (In contrast to Iran, there hasn't been a notably large outflow of smart Turks from Turkey. If you've got some money, Turkey is a pretty okay place to live.)
And then there's an interesting game theory aspect to how hard you would work on building a Bomb in Iran v. North Korea. If you actually got to the verge of a working Bomb, the Israelis would likely drop a bomb on your head, so better to putter around and give each other Powerpoint presentations forever. It's a living! The North Korean engineers aren't too worried about a pre-emptive strike because North Korea already has a deterrent in artillery and small rockets trained on Greater Seoul.
This is all reminiscent of eight years ago when we were assured by The People Who Know that Saddam Hussein was this close to building his own Bomb using crack Iraqi scientists and engineers.