StatCounter and Google Analytics in disagreement

I'm tracking my websites using both StatCounter and Analytics simultaneously
(I assume there's no technical problem with that - please correct me if I'm wrong).
The statistics of both sites differ substantially.
Any idea where this differences come from, and which service is more accurate? Thanks!

 

I would trust google more, they just have more ability to know who the surfers are. They have tracking on alot of pages with their adsense.

I am guessing the google stats are lower as mine always are. This is usualy because google knows more about what is a spam bot or some other hit on your site better than anyone else. While other tracking systems don't trap for that much.

I also have my own stats tracking i wrote on a few of my sites and it almost mirrors google's numbers, over Urchin's. And that is processing server logs, google does its own thing which IMO is much more accurate.

 

I'm getting the same between G and AWstats

 

Google analytics gives more accurate statistics about website in compare with statcounter stats.
Please help me about this difference.