Since it seems to be a common misconception, I'd just like to point out that "Adblock" and "Adblock Plus" are two different extensions made by different people.
Yeah, for the longest time I thought the latter was an enhanced (paid?) version of the former. I can't believe naming browser extensions in a similar manner like this is allowed. It causes nothing but confusion.
I feel really old now, but Adblock Plus was actually forked from the original Adblock. The "plus" part implied it was supposed to improve on the original project.