The two concepts are identical. Your either guessing passwords or guessing filenames usually from a list in both cases. Problem is that one is illegal and can get yo in a lot of trouble and one is not illegal. And just as it is in life when you guess correctly, the legal method gets you one image, the illegal method gets you all the images.
The best things in life are illegal.
back on the subject at hand, if you are looking for a tool to crack photobucket account passwords, this isn't it. Well it is it, but it won't ever be it so do yourself and everyone else in the fusking community a favor and stick to the legal side of hunting. All cracking does is make photobucket tighten up a little more. We don't need that.