We rarely use fjäll about mountains other than the Scandinavian Mountains (plus a few places in the province of Bohuslän).
Sometimes the word is used for mountains in other countries that are similar to our fjäll (they were softened by the glacier ice during the last ice age so they have softer shapes than the Alps), but generally if somebody speaks about fjäll, it's most likely they're talking about a mountain in either Sweden or Norway.
Rather like ''highlands'' and ''The Scottish Highlands'' then?
Also, do you know what ''skutan'' means in the context of mountains. I always assumed that mountain=skutan due to Åreskutan, but after doing this module and googling briefly I can't find anything connecting skutan to mountain (excluding Åre of course).
skuta only means ship to me, but I googled it and it turns out that there was an old Norse word skat or skott (pronounced skut in the local dialect) which meant 'peak' or 'top', so that's where it comes from, now I've learned something today.
PS but highlands are högland in Swedish, e.g. Skotska högländerna. Småländska höglandet in Sweden is not fjäll.
I guess "fjäll" could refer to Scottish mountains too, they are basically the same chain as Scandinavian mountains.
I wonder if Appalachian mountains would qualify, but I guess they are not called that anyway.
Finnish "tunturi" (and based on what I was reading Swedish fjäll too) is defined mainly by vegetation, it's a hill high enough to rise above the tree line (ie. no trees grow on the top of the hill). There might still be grass, lichen and other forms of arctic vegetation.
In Britain we have "FELLS" which is exactly as described by other commenters ie large hills or softer more rounded mountains. The fell areas are in the north of England which are also areas of viking settlement so it could well be how the term entered the english language.
Very interesting, I was not aware of the connection previously. Wikipedia confirms that the English word "fell" comes from the old Norse fjall. I would also like to add that "fell running" is a very popular sport, mostly in the Northern parts of the country (not to be confused with trail running, which is slightly different).