>>36975057That, her eyelashes are different, and her horn is a regular mare unicorn size instead if a bigger stallion one as well. But yes I agree with you 100% on the first two points especially. She just isn't Trixie with those details changed.
The running theory is that it was much easier to change her model to be swappable with all the other characters once she became more of a show regular than a once in a while antagonist. Still blows though.