About Webmaster Tool

I just wanna ask one thing, what is the difference between impression and clicks in the webmaster tool and which tool is better Analytic or webmaster tool.

Impressions means the number of times the ads have displayed. Click means, if someone clicked any of your ads, thats it. say, if somebody has visited your site, the ads will shown up automatically ( creating an impression ), if he clicks your ads, you
get a click. You get paid thru clicks, (though some ads are paid per impressions
which is too low ). so you need more clicks to earn more.