Yes they all go boom. As for why they were invented.. profit margin I would guess.
Black powder is an explosive. The substitute powders were invented to be a cleaner less corrosive powder. They are also not in the same federal classification as black powder. Whether they are cleaner..varies from powder to powder. Also they do not weigh as much as black powder but supply the same power. But if I had to guess it was for the fact they wanted a cleaner powder that got more shots per pound then the conventional black powder.

We always look for something better.