- Each computer player has its own AI code behind it. Not a script but literally its own C++ class.
- Each player has its own unique dialog tree. They say and act differently.
- Each player has different abilities similar to Civ IV industrious or organized.
- Each player has its own strategies, own military tactics.
I'm not sure how one could argue that Civ IV's players are more different from one another than GalCiv II's aliens.
As much as I like Civ IV and its AI, the victory conditions in it are not significantly different from the GalCiv AI. It's not actively trying to get a cultural victory, for instance as far as I can tell. It can try to build the space ship but that's essentially another wonder.
In GalCiv, certain players will actively try for one type of victory path over another. The Drath will pay off races to try to keep everyone busy while it builds influence. The Drengin go the straight line conquest. The Altarians try to build alliances over time.
The original poster's argument is that GalCiv's AI isn't as distinct from differnet players than Civ IV's. I think that is factually incorrect. I haven't talked that much to Soren on this but given that the SDK will be out soon, I suspect you'll find that the difference betwee players in Civ IV is largely variables.
For the record, I love Civ IV and think it has a very good AI. I just don't think it's accurate (even in the remotest sense) to assert that the GalCiv AI players are particularly similar in how they actually play the game. The fact they have their own dialog trees would count for something you'd think even if that part's cosmetic.