User blog comment:Diyartifact/Shepard's adversaries/@comment-1895174-20120408234519/@comment-1388547-20120409220109

Sovereign, Saren, and the geth all managed to be separate entities. Saren was indoctrinated, and was working for Sovereign, but I got the impression he had a fair amount of autonomy -- he was a character in his own right, not just Sovereign's puppet. While it's not spelled out, I also got the impression the geth were also their own entities: they worshipped the Reapers and followed Saren's orders because he was their representative, but they were not simple slaves.

There's much less distinction between Harbinger, the Collector General, and the Collectors. Again, this is personal impression rather than something spelled out in the game, but to me it seemed that the Collector General was little more than a relay for Harbinger's control -- at the end of ME2, we discover that Harbinger has been possessing the General for the entire game. Mordin also implied that the Collectors were little more than part-living, part-synthetic manipulator devices used by their masters. While the geth worshipped the Reapers, I don't think the Collectors had enough brainpower left to even form the concept of doing anything other than their carrying out their immediate orders.

In my view, while Sovereign, Saren, and the geth were all distinct from each other, Harbinger, the Collector General, and the Collectors were essentially the same entity.