A very common question we get from clients is why do Google Analytics and Google Adwords report different traffic data for our campaign? The short answer is:
Google Analytics reports ‘visits’. A ‘visit’ is a 30-minute session on your site. Google Adwords reports ‘clicks’. One person can click on your Adwords ads 3 times during a 30 minute session. So that would report as 3 clicks in Google Adwords, but only 1 visit in Google Analytics.
Here is a link to a very useful Google Support article that will explain this common issue further….