I would think that fog and smoke would reflect differently. My folks heat with wood, and growing up I got to deal with at least one down draft a year that filled the house with smoke. I always got the impression smoke didn't reflect back as much.

If I had to take a guess, I'd say it is a matter of water being water, and having a very high reflectivity, compaired to things reduced to the size of a couple of a bit of dust. Also, since water likes to take a round shape, which reflects light evenly, it might increase the glare. I've never looked at captured smoke, but I imagine that it's surface is fairly irregular.

And yes, I realise my geek is showing.