Google Analytics records a visit when a user opens a page, moves the mouse, clicks buttons and navigates between pages. It is useful for analyzing what visitors do on your website. Some data may be missed due to security software, blocked cookies, patched/new browsers, ad blocking technology or fast browsing (not staying on a page for at least 2 seconds). The stats provide a very rich set of data for User Experience analysis, but they are not providing real numbers.
Server stats (LVSYS Stats) record all pages sent to real users and robots. You can access them from All Tasks>My Account>Reports>Page Hits. The data is further sorted between browsers, computers, mobile devices and robots. The server stats provide accurate, real numbers.