Chrome adblockers don't block ads, they "hide ads", unlike FF Adblock.

So the ads are still loaded, but you don't get the visual clutter (I guess that the point of most adblockers), on Firefox, ABP will stop ads from loading in the first place.

AFAIK

Actually, Adblock for Chrome can block ads too, but I think not all of them. It happend once Google let in by mistake some code from Webkit, that allowed for this to happen. And then they didn't remove it anymore.

Here's what Adblock's author says:

"New in version 2.0: Ads are actually blocked from downloading now, instead of just being removed after the fact!"

It wasn't a mistake. A google engineer pointed it out on the chrome bug tracker saying you get this feature for free now with webkit