In the unrated version of Curse of Chucky the Barb death scene is more gory. (You see Chucky's knife stab into her eye). In the rated version of Curse, we see the back of Barb's head, and see Chucky's body lean forward and then hear her scream.
Ian's death is slightly different in the unrated and rated versions of the movie, in the rated version, we see from Chucky's point of view, Ian's lifeless body for 10 seconds before it cuts to chucky's line "Maybe not.." In the unrated version, Chucky looks back for another 5 seconds before saying his line.
In the unrated version, we see a cameo by Alex Vincent as a now grown up Andy Barclay. When Chucky comes out of Andy's package, he notices a military academy diploma, a picture of Kyle from "Child's Play 2" and notices Andy with Karen from the first "Child's Play" film. When Chucky notices Andy, he says "Andy!" and Andy pulls out a gun and replies "Play with this!"