Pictures of the minis I've seen on the internet makes it look like a lump of plastic because it's so small....what's the average size we're looking at here? Any problem distinguishing a mold from the next?

No worries finding which piece is which, the adventurers are about 15 mm tall

The only ones I have "trouble" with is determining the Knight from the Adventurers at a glance, because both types hold swords. However, the Knight has a shield and is a little bulkier, so closer inspection makes them easy to tell apart, but at first glance they can meld together.

The rest of the minis, while small, are very easy to discern though.