there are distinctive differences between carob and chocolate. Carob is naturally sweet, not bitter, and does not have the pH of chocolate, so recipes do not need to have as much sweetener. Carob is caffeine-less; chocolate has a form of caffeine. People who expect carob to be an even trade for chocolate or cocoa are disappointed, although carob products now taste a lot better than they used to. The carob pods are eaten -- visiting a friend in Israel, she put a bowl of the pods out with other snack food. Understandably, they are better fresh. When the pods are dried, they become leathery.

its used as a substitute for chocolate in baking...here is the details from wikipedia.
http://en.wikipedia.org/wiki/Carob
hope this helps