Well the main dfferences are in <img src="/ubbthreads/images/graemlins/beyond.gif" alt="" />
1)it is a bit more linear....i.e there is an Act system.
2)the skill system is more complicated.
3)there are more skills avialable.
4)More stats.e.g speed and survival as well as the usual agility,strength
5)There arent many races(no orcs or elves) but new creatures and one new race.
6)You can advance skills buy paying a trainer.
7)Battlefields where there are loads of dungoens/quests to complete(they are optional)
8)Controlling two characters means you can advance them in different disciples..e.g one a mage and another a theif.
9)You will find out alot of about the contintuing <img src="/ubbthreads/images/graemlins/div.gif" alt="" /> storyline.
10) <img src="/ubbthreads/images/graemlins/beyond.gif" alt="" /> is not set in Rivellon althougth you will visit Rivelon occasonally.
11)There is very little greenery but different landscapes which may or may not appeal to you.
12)There is no reputation as in <img src="/ubbthreads/images/graemlins/div.gif" alt="" />..you do have a reputation but it doesnt effect how people treat you.
13) Slightly less item interaction.
14) Different arrow types and more resistances( not just fire resistance but also earth).
Those are probably the differences...well those which i noticed.