Google Analytics and AWStats are both tools used to measure website traffic and related site visitor metrics, which can then be analyzed to optimized your digital marketing, user experience and server performance / content distribution strategies. In a nutshell, one can say Google Analytics is more user centric while tools like AWStats and Webalizer are used more to monitor and optimize server performance and speed of content & web service delivery. Both give detailed reports regarding which pages are garnering the most visits, from which sources, at what times of the day, what the average visit duration is, among many many other things. But the stats shown by them can differ due to the following reasons:
- Most search engine crawlers and spiders do not run Javasript code and hence Google Analytics doesn’t treat them as website traffic while AWStats does. AWStats has the capability of detecting visits from humans and non-humans and at the same time it classifies them as Viewed and Not Viewed traffic respectively. AWStats maintains a list of IPs that belong to spiders or crawlers, but this list might not always be exhaustive, so, it is not cent per cent accurate.
- AWStats counts users by their IP addresses while Google analytics uses browser specific cookies for reporting the same. Single users with dynamic ips and multiple users from a single ip are both treated as multiple users in AWStats. In Google analytics, if the user keeps on clearing the cookies between visits, that also counts as multiple users. Hence, traffic numbers can be overstated or understated by both, just due to different reasons.
- What counts as a user session also varies between the two tools. Google Analytics expires user sessions after 30 minutes of inactivity whereas the default session length in AWStats is 1 hour. This obviously causes differences in session-related metrics between the two.
- Both tools can also display different values for the same metric due to time zone settings - which are easily overlooked. Your Google Account timezone settings could differ you're your server timezone settings - so you might not be really comparing data from the same time frame.
- While AWStats reports in real time since it is sitting on your server, Google Analytics reports data two days old, unless you’re using Google Analytics Premium.
Both have merits and demerits but the most important factor to really consider is your set of objectives. AWStats and Webalizer are more to do with website and server performance/network and bandwidth usage and optimization. Google Analytics is more useful from a business, end-user point of view - tracking the actual demographics, behavior, sources and more of your audience.