The difference is, Sam is tiny especially in that area of her body. I met Sam a few years ago after she did her own concert tour, and she’s like a tiny little doll.Sam Barks just did several months of Frozen shows while pregnant, so there's obviously ways and means to get around it. I think the bigger problem will be Carrie's attitude; I'm sure by December everything will be too difficult for the pregnant princess.
I imagine she just looked ‘normal’ when she was a few months. I don’t think it will be the same for Carrie. I’d be interested to know whether she is showing yet or not.