In English, Em-dashes have a couple of different uses, but in the most common use they are usually set closed (no spaces on either end), though some styles set them with a space on either end. En-dashes have one use (similar to that of em-dashes, which is used varies by house style) where they are usually set open, and a number where they are usually set closed.

Given that the rules for these marks aren't particularly consistent, or even fixed, in English, I think its safe to say they aren't consistent for the same piece of punctuation across all uses in all Indo-European languages.