The standard South Korean dialect is based on the Seoul (서울) dialect, while the North Korean dialect is based on the Pyongyang (평양) dialect. Seoul (서울) and Pyongyang (평양) are the capital cities of the two respective countries. Although the standard North Korean dialect uses a different intonation and has a slightly different pronunciation system than the standard South Korean dialect, it’s not so different as to cause call the two dialects a separate language.
For example, the South Korean word for practice is 연습, while the North Korean word for practice is 련습. In this case, the two words for practice is similar and when you hear it in context, you may not even realize that the two words are different in pronunciation. The same goes for the word “cold water”. In the standard South Korean dialect it’s 냉수, while in the standard North Korean dialect it’s 랭수. For native speakers of both the South and North, it’s not a big deal. In other words, the pronunciation difference is not that wide enough to cause a miscommunication meltdown.
Of course there are times when the vocabulary is vastly different between the two dialects. The South Korean word for friend is 친구, while the North Korean word for friend is 동무. The South Korean word for friend has much of the same meaning as “friend” does in English. 친구 means buddy, pal that kind of thing. However the North Korean word for friend has a slightly different meaning. The North Korean word for friend is similar to the Russian word for comrade or collegue. In other words, the North Korean word for friend has communist implications and means something like “brotherhood” much like in the Marxist sense.
In some ways I think the North Korean dialect might be easier for English speakers. For example the word for chopsticks in the South Korean dialect is 젓가락, but in the North Korean dialect it’s 저가락. The same goes for the word tree leaf. In South Korean it means 나뭇잎. In North Korean it’s 나무잎. I think it’s harder for English speakers to juxtapose their tongue to pronounce the ㅅ in 젓가락 and 나뭇잎.
Ok, I’ll leave you to ponder the differences. See ya!