There is an important distinction between clicks (such as in your AdWords reports) and sessions (such as in yourAudience reports). The Clicks column in your reports indicates how many times your advertisements were clicked by users, while Sessions indicates the number of unique sessions initiated by your users. There are several reasons why these two numbers may not match:
- A user may click your ad multiple times. When one person clicks on one advertisement multiple times in the same session, AdWords records multiple clicks while Analytics recognizes the separate pageviews as one session. This is a common behavior among users engaging in comparison shopping.
- A user may click on an ad, and then later, during a different session, return directly to the site through a bookmark. The referral information from the original session is retained in this case, so the one click results in multiple sessions.
- A user may click on your advertisement, but prevent the page from fully loading by navigating to another page or by pressing the browser’s Stop button. In this case, the Analytics tracking code is unable to execute and send tracking data to the Google servers. However, AdWords still registers a click.
- To ensure more accurate billing, Google AdWords automatically filters invalid clicks from your reports. However, Analytics reports these clicks as sessions on your website in order to show the complete set of traffic data.
Note: Above information is based on https://support.google.com/analytics/answer/1257084?hl=en