"From the outside?"
What's the difference between "außen" and "draußen"??? They both mean "outside"...
Because außen is an adverb rather than a noun (it is technically possible to turn it into a noun but in normal conversation you probably never hear it).
So, if you said that "Ich komme von Außenseite", would that be correct since it is a noun?
I’m afraid not. For one thing you’d need an article: von der Außenseite. More importantly however, Außenseite quite literally means the outer side of something in German. For example if we’re talking about a window, its Außenseite would be the outer glass pane. It is not used to refer to the general area “outside” – that would be außen or draußen (or as a preposition “outside the window”: außerhalb).
Btw, a small clarification in case my original correction to PhilipMars9 generated confusion: I did not mean that you can’t combine the adverb außen with a preposition like von; in fact you can. What I was trying to say was that an adverb like außen cannot take an article because only nouns take those.