In German you use en-dashes with spaces, whereas in English it’s em-dashes without spaces. Some people dislike em-dashes in English though and use en-dashes with spaces as well.
In English, typically em-dashes are set without spaces or with thin spaces when used to separate appositives/parentheticals (though that style isn't universal even in professional print, there are places that aet them open, and en-dashes set open can also be used in this role); when representating an interruption, they generally have no space before but frequently have space following. And other uses have other patterns.
In British English en-dashes with spaces is more common than em-dashes without spaces, I think, but I don't have any data for that, just a general impression.
Similarly, French puts spaces before and after ? ! while English and German only put spaces afterwards.
[EDIT: I originally wrote that French treats . , ! ? specially. In reality, french only treats ? and ! specially.]