Swedish mountains are rounded on top and sharp on one side. The Alps are sharp everywhere. The difference is not age in the way people assume.
The usual explanation is that the Swedish mountains are "older and more worn down". That is true, but it is only the first third of the story, and the interesting part is the rest.
1. A range that was once alpine
The Scandinavian mountains formed during the Caledonian orogeny, when Greenland collided with Scandinavia around 400 million years ago. According to the Swedish Museum of Natural History the range consists of stacked nappes: large sheets of rock transported hundreds of kilometres eastwards and thrust up over the old basement.
Back then it was a range on the scale of the Himalayas. Then nothing happened for a very long time, apart from erosion. The range was worn down until the area was close to flat.
2. The flat landscape was lifted again
Here is what explains the rounded summits. During the Tertiary a vertical uplift of western Scandinavia took place, and what was lifted was therefore not a mountain range but an almost planed-off landscape.
That is why so many Swedish mountains have broad, nearly flat summit areas at roughly the same height. They are remnants of one and the same old surface, raised up. Standing on bare mountain and seeing every horizon sitting at the same level as far as you can see, that surface is what you are looking at.
3. The ice cut the valleys, not the summits
Then came the ice ages. And the ice worked very differently in different places.
Where the ice gathered and moved quickly, that is, in the valleys, it dug hard. The result is the broad U-shaped valleys: flat floor, steep sides, tributary valleys cut off abruptly. Syterskalet at Hemavan is a textbook example. On the Norwegian side the same kind of valleys reach all the way to the sea and are then called fjords.
Up on the high plateaus the ice was thin and moved slowly or not at all. Very little was removed there. Some summits stood above the ice entirely, like islands in a white sea, and are called nunataks.
The combination gives the typically Swedish result: a mountain that is soft and rounded when you walk up it from one direction, but stands like a wall from another. Helags is exactly that, and it is also why the glacier has survived in the shade beneath the face.
And why the Alps look different
In the Alps the mountains are both younger and higher, and there cirque glaciers worked around the same block of mountain instead of a thick ice sheet passing over it. That is how sharp pyramids such as the Matterhorn could form.
Put briefly: alpine shapes appear when ice eats inward from the sides. Scandinavian shapes appear when ice passes over.
What that means when a landscape becomes a piece
In practical terms a Swedish mountain is harder to render than an alpine peak.
A spire reads itself. A rounded plateau with a steep face on one side does not, especially once the elevation range is compressed to centimetres. The window therefore has to be chosen so that both the plateau and the valley around it are included, otherwise the whole square becomes an even slope with nothing to hold on to.
That is also why the height is scaled up, which we have covered in the article on vertical exaggeration. The whole range in one sweep is best seen on the Sweden piece, where you can watch the old surface tilt away eastwards towards the Gulf of Bothnia.