Many people use either term for a couple of different trees.
If you have ever travelled outback Australia you can get to see both.
The most common error I hear is calling the Queensland Bottle tree a Boab.
There's a difference, and rather than repeat what is already out there here's some links.
Queensland Bottle tree Australian Boab tree
Now out there in the bush is a few hollow ones, and you guessed it right. Back in the ole 1890's the cops used them as prisons, locking up their prisoners overnight as they transported them.
Prison tree below. There's a few though, Derby, Wyndham etc.
Now Boab's unlike the Queensland Bottle tree are deciduos and fruit, they get these whopper nuts!
However in suburbia most trees you'll come across are the Queensland Bottle tree, Brachychiton rupestris ... which is not a boab. They dont get as big and have a fine leaf, beautiful trees just have room for their swollen trunks.