[Jongseong]

You've got the gist, but North Korea does use tonnes of Sino-Korean words, which are like words of Greek and Latin origin in English. You can't simply eliminate such words from the language altogether. What you can do is to favour pure Korean words over Sino-Korean when coining new terms or standardizing terms for technical usage. So North Korea might use a bit less Sino-Korean than the South (I'm not even sure though, because there are other factors such as loanwords in South Korea displacing Sino-Korean words there). But this makes barely a blip on the language as a whole since so many basic words in Korean are Sino-Korean. Even most North Korean terms you're ever likely to hear are Sino-Korean: Juche, Son'gun, Chollima, Rodong missiles...

[hcolomb]

To add on to this: In South Korean newspapers you'll often find Hanja (the original Chinese characters) on news sites or in the paper or even on the news. It may be simply to clarify a phrase, or for when someone has passed away, there's a character for that. So South Koreans may not know a lot of Chinese characters, but they know the basics and they are quite aware where many words come from-- In North Korea to emphasize their Korean-ness they have little to none of these Hanja anywhere, they don't learn it in school like a South Korean child would, either.

On top of this, you'll find that those English loanwords are almost nonexistant in North Korea. Where South Koreans will simply say "Ice cream", North Korea has the word "얼음보숭이" which literally translates to "ice fluffly thing".

There's also differences in the speech styles (a very complicated and extensive topic in itself) and verb endings. NK prefers some styles where SK prefers others-- But like it was said farther up, the difference really comes down to something like US/British English, obviously different but still very mutually intelligible.

[Jongseong]

Actually, they do teach Chinese characters in school in North Korea; it is a common misconception that they don't. They teach 3,000 characters, which is numerically even more than the 1,800 characters taught in South Korea in school. But as you said, in North Korea you don't even see the very limited usage of Chinese characters in newspapers that you see in South Korea, so it is not much beyond a subject you learn in school. You could say the same about the situation in South Korea, though, since the usage of Chinese characters is really, really limited, mostly to certain newspapers.

The notion that North Koreans say 얼음보숭이 (ŏrumbosung'i) for "ice cream" is a bit of a myth. The authorities in North Korea did indeed introduce this word as a part of a linguistic purification effort, but it doesn't really seem to have caught on. A 1962 North Korean dictionary only has 아이스크림 (aisŭk'ŭrim) "ice cream", just as in South Korea. A 1981 edition of another dictionary and a 1984 encyclopedia introduce 얼음보숭이 (ŏrumbosung'i), but the official dictionary that appeared in 1992 again has 아이스크림 (aisŭk'ŭrim) "ice cream" and not 얼음보숭이 (ŏrumbosung'i). The 1992 dictionary also has 에스키모 (esŭk'imo) "eskimo", which in North Korea is a popular everyday word for "ice cream" which comes from a name of a brand that was popular there.

You have plenty of examples of South Korean language authorities introducing "purified" (often pure Korean) words to replace loanwords, which don't necessarily catch on. For "stapler", the official South Korean dictionary has the pure Korean translation 찍개 (jjikgae), for instance. But I have never seen this term in the wild—instead, people say 스테이플러 (seuteipeulleo) "stapler", or more commonly, 호치키스 (hochikiseu) "Hotchkiss". There is a limit to how much official language policy can dictate actual usage, whether it is in North or South Korea.