"Those cities are not in Scandinavia but in Finland."
Translation:Nuo kaupungit eivät ole Skandinaviassa vaan Suomessa.
As a native I love these questions - they really make me think. First of all, "mutta" really isn't ok here. My explanation would be, that "mutta" kind of takes something away from the first claim - f.ex. "I liked the food mutta it was too cold". Or "I love dogs, mutta I'm allergic". "Vaan" is neutral and compairs two more or less equal options. "I don't like red vaan I like yellow". or "I didn't go shopping, vaan I went to the movies". If you say "I don't like red, mutta I like yellow", it sounds like you need to emphasize the fact that you do like at least some colors. If you use "vaan", we all know already from the beginning that you like colors, but you are just telling us which colors. One example more of the difference: "I don't drink alcohol, mutta I like to party". You still like partying, even if you don't drink. "I don't drink alcohol, vaan I like to party". In this case you tell us that drinking is almost contradictory with partying and you definitely prefer partying instead of drinking, because they cannot be done at the same time. Good question and a challenge to explain. Ask away, if it still bothers you.