C3PO was a fussy pessimist in Star Wars, and a whining, complaining, annoying pest in Empire.
Leia (prounounded Lee-ah) was a feisty firebrand in Star Wars - while Leia (pronounded Lay-eh) was, well, a whining, complaining, PMSing shrew through most of Empire.
The changes were primarily in the dialogue, and were - I believe - due to the tonedeafness of the screenwriters who mistook feistyness for obnoxiousness and fussiness for annoyingness.
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