Some interesting things that have happened since the war:
- Korean national identity movements have been strong in both countries. In the North, an effort towards language "purity" has changed some of the vocabulary and eliminated Chinese characters from written communication. In terms of vocabulary, loan-words from other languages were replaced with "pure" Korean words. For example, South Koreans use "computer" (컴퓨터), while North Koreans have used (걔산기) (Gyaesongi) which means something else (though they've started to use 콤퓨터, an almost homophone for the the South Korean word and loaned from English). The article gives another great example with "donut". In the South, a preference to eliminate Chinese writing as a practical matter of preference has happened as well (these days it's pretty uncommon to see outside of maybe newspapers, people just can't be bothered to remember all of the characters), but knowledge of Chinese characters is still highly prized as a matter of scholarship and education. But the South also has more quickly incorporated loan words from various countries and you'll find loads of English and English-like loan words (sometimes filtered through neighboring Japan or China) ending up in the language and written in Hangul all over the place. French is also common, but usually written in Latin characters for commerce reasons.
A recent cooking show on South Korean TV involves teams of two cooks preparing traditional foods, and one of the teams is from the North. There's no trouble communicating with the Northerners, though my wife lets out chuckles on occasion as they let slip stereotypical sounding communist slogans from time to time as they face difficult cooking challenges - "the North has nothing but strength!" as they work a noodle press by hand.