I clicked on the advertise here tab on one of my Adbrite ads on my site. I got this. If you look carefully it shows that my unique users per day is 140 whilst my page views per day is 110. My Analytics is completely different. Anywho, the point of this is I don't like Adbrite, the ads are terrible, there eCPM isn't anything special, and the publisher data they give you is next to nothing.
Yes a lot of site tracking stat is not same result. But nowsday people is only give important to google analytic coz it corelated with adsense earning.