They might have assumed it was a subdivision of phpBB or something, I've encountered several people who have thought that so it's still a decent question despite Google being able to easily find the answer.

Anyway, if you still haven't decided on which free alternative to use, give MyBB a shot as someone else suggested. It has a much better administrator panel than phpBB and while it doesn't have as many mods/themes, most of the popular mods are available for it and there's still a handful of nice free themes if you're not much of a skinner.