Clicks The Clicks column in your reports indicates how many times your advertisements were clicked by users
Sessions Sessions indicates the number of unique sessions initiated by your users.
Diffrence 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.
2 Sessions vs. Users
Sessions Analytics measures both sessions and users in your account. Sessions represent the number of individual sessions initiated by all the users to your site. If a user is inactive on your site for 30 minutes or more, any future activity is attributed to a new session. Users that leave your site and return within 30 minutes are counted as part of the original session.
The initial session by a user during any given date range is considered to be an additional session and an additionaluser. Any future sessions from the same user during the selected time period are counted as additional sessions, but not as additional users.
Sessions vs. Entran
Pageviews vs. Unique Pageviews
A pageview is defined as a view of a page on your site that is being tracked by the Analytics tracking code. If a user clicks reload after reaching the page, this is counted as an additional pageview. If a user navigates to a different page and then returns to the original page, a second pageview is recorded as well.
A unique pageview, as seen in the Content Overview report, aggregates pageviews that are generated by the same user during the same session. A unique pageview represents the number of sessions during which that page was viewed one or more times.
Sessions vs. Entrances
Sessions are incremented with the first hit of a session, whereas entrances are incremented with the first pageviewhit of a session. If the first hit of the session is not a pageview, you may see a difference between the number of
Avg Time on Page = Time on Page / ( Pageviews - Exits)
Avg Session Duration = Session Duration / Sessions