Hi Mary,

I am in no way a stone expert but true Carrara and true Calacatta are from the same region in Italy. There should be no difference in durability and maintenance. It's more a matter of aesthetic, The backgroubd of Carrara is much more grey whereas Calacatta is white.

There are Chinese and Indian versions called Carrara and Calacatta - they're usually spelled slightly different and are very crystalline in appearance. They look nothing like the smooth appearance of Italian marble. I've been told that they are much softer and more prone to chipping, scratching and even in some cases crumbling. There's a YouTube video of a tile setter trying to cut Chinese Carrara trim pieces and its crumbling like chalk.

Hope this helps!

I don't think there are big differences, just make sure it is sealed and resealed every year or two.
Although typical stains in shower are yellowish, so it can be little more hidden within Calacatta veins than Carrara.

Here is a link that might be useful: Yellow stains on Carrara