The distinction might be so obvious people are overlooking it. I would suspect the difference between a quote "goodie hut" and a dungeon would be that a goodie hut is a single building that requires no exploration and only has the potential for one battle. A dungeon on the other hand I suspect would be larger (several tiles in size) with multiple rooms or levels. The dungeon would also have the potential for multiple battles with a boss or mini-boss in the final level / room / whatever. That is my take on the subject anyway. 

Based on BoogieBac's last post it seems like the distinction probably has nothing to do with combat. BoogieBac's example of a troll encampment makes it seem like it will be something you can interact with on an ongoing basis - the trolls could possibly stray from their encampment and cause problems for your kingdom, or you could befriend them and recruit trolls from it now and then, etc. So my guess is that the only distinction is that goodie huts occupy one tile on the map, and WYSWYG, while dungeons are map objects that lead to a larger area that must be explored and all.

"Goodie hut," as far as I know is just a term taken from the Civilization (or maybe colonization?) series - where there were literally lone huts on the map that would do something - either give you a bonus of some sort, vanish your explorer, spawn barbarians, etc. The term has grown to mean anything of the sort, regardless of its graphical content. Considering the rarity of magical creatures in Elemental, I wouldn't expect a troll encampment to be very big at all - so a single tile would be believable to me. If a troll encampment could be the size of even a small human city, then I'd expect to see hundreds of not thousands of trolls and that does not sound like what Stardock has in mind.

mythical doesn't equate to magical if you ask me. I would also guess that they live in Europe if trolls were real.

Goodie Huts: For All Your Bear Cavalry Needs

That's a good distinction, though trolls are frequently considered are at least partly magical given they can regenerate to fully healthy even when dead, unless burned. Dragons probably fall under mythical as well though, unless you're considering in some mythos they can cast spells or glamours or some such.

I find a lot of more modern dragon stories actually create a 'reason' that dragons breath fire other than "magic".  Often it comes from some sort of organ that produces a flamable gas (which happens to some extent in real life, it just doesn't come out of our mouths, nor is it expelled in amounts that it could be used for anything other than accidently clearing an elevator) and often lighting it is accidental (either because the gas natuarally combusts when in contact with oxygen, or there is another reason it gets hot enough to ignight)  hints: sleeping dragon puffing flames with its snores

Whats more, a lot of dragons that european dragons that come to mind (in particular the ones found on christian cathedral walls and paintings) did not seem to breath fire at all, but were rather just massive serpant or lizard like creatures of note.