Despite having similar names, AdBlock (https://getadblock.com) and Adblock Plus (ABP) (https://adblockplus.org) are unrelated products developed by different companies. The reason they're similarly named is an interesting bit of internet history:
Long, long ago, somebody (not us) created a Firefox add-on called Adblock. Later on, another team created a different Firefox add-on and adopted the name Adblock Plus (ABP). When Google Chrome came along, the Adblock Plus team wasn't interested in supporting the new browser. Which is why Michael Gundlach created an ad blocking extension he decided to call AdBlock for Chrome. Later on, the Adblock Plus team decided to support Chrome as well. Over time, both AdBlock and ABP added support for additional browsers and platforms. And that's why the two most popular ad blockers have such similar names.
Other "AdBlock" Extensions
People often ask us about extensions that are named similarly to AdBlock and Adblock Plus. Their logos often look very much like AdBlock's. Even more confusing, since our code is open source, some of the ad blockers themselves look very much like AdBlock. Where there is a clear violation of our trademarked logo or other intellectual property, or if our code has been adapted to infect users' computers with adware, we report the developer to Google, Mozilla, or Apple, as appropriate. Product names can't be trademarked, however.
Since logos and names can be misleading, the best way to make sure you're downloading the real adblock is to do so directly from our website.