No it's not the same. Note there are medium and long as well.

That said I always use -- myself. I don't think about pressing some keyboard combo to emphasise a point.

You are absolutely right — most internet users don't know the specific keyboard combination to make an em dash and substitute it with two hyphens. On some websites it is automatically converted into an em dash. If you would like to know more about this important punctuation symbol and it's significance in identitifying ai writing, please let me know.