It doesn't. Noscript blocks scripts and plugins from executing on the page and AdBlock blocks a specific list of ads.
Ghostery blocks a list of trackers such as google analytics, KISSmetrics, and facebook social plugins[1]. Ghostery generally won't affect the page at all except in invisible ways, but it will remove Like, Tweet, +1, etc buttons to prevent requests from being made to Facebook/etc.
You can also fine-grain set Ghostery to allow certain trackers, like Google+ buttons, while still blocking all the others.
Adblock with Easylist Privacy compares to this though. However you won't get ghostery's eye opening popup with it. I use both in conjunction just to be sure.
