North and South Korea were once a unified country. They shared culture, and of course language before but because of the separation since the Korean war, this led to many differences in many aspects including their language.
South Korean language is called Hangugeo (한국어) while North Korean’s language is Munhwao (문화어). Munhwao is the standard NoKor language which is mostly spoken in their capital, Pyongyang, and was officially established in 1966. It still has the same roots as the Seoul dialect so it is possible to still have good communication between two speakers. That’s why in the drama ‘Crash Landing On You’ the characters from the North and South can still understand one another.
The main difference between the two languages is how they use loan words and Sino-Korean Language or Hanja (Korean words with Chinese roots). It is very fascinating how NoKor formulated their words. Kim Ilsung, the former leader of North Korea, did not want to use much of foreign language so they made Korean words for words like Ice cream, Hamburger, and Cellphone, unlike in South Korea. Here are some great examples below.
An Ice Cream in Sokor is just a-i-seu-keu-rim, but in Nokor they say Eorum gwaja. Eorum literally means ice and gwaja is a snack so together it is an ice snack.
A Friend in Sokor is Chingu and it is Dongmu in Nokor. Dongmu means comrade and it greatly shows the North’s strong communist belief.
The Sign Language in Sokor is Soohwa while it’s Sonkarakmal in Nokor. Sonkarak literally means finger and mal are words.
South Koreans use almost the same with english word ”shampu” while North Koreans use ”meorimulbinu.” The word means is a combination of meori (head), mul (water) and binu (water).
Here are more words from AP by Kim Hyungjin (2015):
“— South Koreans use the English loan word ‘juice’ but North Koreans say ‘danmul,’ or ‘sweet water.’
— South Koreans watch a ‘musical’ but North Koreans see a ‘gamuiyagi,’ or ‘music and dance story.’
— The sea creatures that South Koreans call ‘cuttlefish’ are known in North Korea by the word South Koreans use for ‘octopus.’
— A ‘dosirak‘ is the South Korean word for a lunch box, while North Koreans call it a ‘bapgwak.’
— South Koreans use the English loan phrase ‘skin lotion’ but it’s ‘salgyeolmul,’ or ‘skin water’ in the North.”
Pyongyang dialect is said to be softer than the Seoul dialect. The ㅈ is /j/ in Sokor and it is /ts/ in Nokor. Their intonation also has a big difference. North Koreans have more ups and down in intonation. When speaking a declarative in Seoul, it usually ends in a falling intonation. In Nokor it ends both with raising and falling.
Both countries can surely communicate like how Americans can speak to British and Australians but will have trouble understanding some unique words and slangs.
Watch here for more understanding between the two languages: