Just in case you didn't read my previous post backwards, I'll take a stab at it. /wiki/List_of_countries_by_Social_Progress_Index lists countries by "social progress", which they define as basic human needs, foundations of well-being (whatever that means), and opportunity. (I didn't cherry-pick the source; this is the first one I found that included North Korea.) The data are from 2015. On this ranking, Denmark is 8th, with a score of 86.63, the US is 16th (82.85), South Korea is 29th (77.7), and North Korea is 134th and last, with a score of 20. (Something like 60 countries didn't supply enough data to be ranked at all.) North Korea is 11.42 points behind second-to-worst (Central African Republic). So by this measure, (Denmark - US) = 3.78, and (South Korea - North Korea) = 57.7. So, yeah, I'd say that my statement that " the difference between Denmark and the US is massively less than the difference between South and North Korea" is quite accurate.

You could also look at the Satisfaction with Life Index (https://en.wikipedia.org/wiki/Satisfaction_with_Life_Index), except that it doesn't seem to list North Korea at all...