In the UK iteration, the pacing is better, the number of characters has been reduced, several meandering side stories have been removed, and several new, very good elements and characters have been added. It goes hard, it is intense, it goes further, it asks more pointed questions, it is more epic.
The Swedish one is 2×10 episodes, the UK one is 3×8 episodes, and they diverge pretty much from the start. Series 2 and 3 of the UK one don't really have any corresponding plotlines in the original.