The below only applies to 3rd edition play; currently we are playing 5th edition which I have not made any significant changes or table judgments for.
Races – changes to the existing races in the book as well as the inclusion of formal Dalun-specific subraces
Core Classes – enhancements to most of the classes
Skills – some additions to existing skills
New Feats – feats taken from other sources and made official in the eyes of the DM as well as additional feats for mostly warrior type classes
Feats – improvements to some of the lacking feats
Game Rules – alterations to the game’s core rules for the sake of balance
Spells – DM interpretations on specific spells