Is there a place where the differences between both documents are described?
Aside from the usual typo corrections and a few minor text edits (none of which are substantive, but all of which hopefully read a touch better), there's a new stat block (Arick, who might engage one of the heroes in a sparring match), the new map, and a new sidebar that explains how to run things if the heroes don't have the MacGuffin from Adventure One.