-Mixing is getting the right levels for each element of sound (voice, music, FX) at a point given.
-Editing is selecting, ordering and cutting the sounds that will play.
Happy to be corrected if I am wrong or someone can explain it better!
Mixing for me is to do with balance and blend. Editing is changing something to make it different - so is more a technical skill, with musical skill perhaps less so. Balancing is more musical, with less technical. I used to like the job title balance engineer - which sort of explained it.
I noticed that you put this in the Cafe, but we do have a Sound forum, and several members are experts there, including at least one Hollywood sound editor (Noise2). In fact I would say that the DVXUser Sound forum has the highest signal-to-noise ratio of any section, no pun intended.
I'm not saying you need to repost this there, but I would recommend it to anybody, for future posts. It's a hidden gem!