The difference between Google Analytics and JetPack is like the difference between Godzilla vs. Monster Zero (only one will win).
With a nod to the classic Kaijū film, we have our own Godzilla vs. Monster Zero—two heavyweights of analytics for bloggers. The most distinct thing to remember about Jetpack is that it has nothing at all to do with the serving or reporting of ads and revenue while Google Analytics does by way of its integration with the Doubleclick for Publishers platform (DFP).
Each (Godzilla or Monster Zero) counts traffic in a different manner. Here at BoardingArea, we strictly use Google Analytics as it's the industry-standard solution for measuring traffic and it also has close ties with the ad-serving network of DFP. Here's a little bit of why it's not a good idea to compare one set of analytics to the other:
JetPack displays stats by Greenwich Mean Time, whereas Google uses a locally specified timezone.
Google Analytics does a better job of excluding hits by spam bots and spiders, and ultimately it is more accurate after filtering data that will often match very closely server files.
Javascript-based analytics like Google Analytics vary in accuracy because many people have Javascript blockers installed on their browsers. Since the major advertising platform is Google Publisher (DFP was formerly Doubleclick) it is considered the default analytics tool so that it matches stats for advertisers.
The error rate because of Javascript blockers is considered to be roughly 5-10%.
Google Analytics is showing the number of visits, while WordPress stats are showing the number of views.
Google Analytics uses a default time per session of 30 minutes, while WordPress has a different default time per session.
Javascript calls to a page can be counted differently if cached or not and there is a slight difference between WordPress and Google Analytics on how cached pages are treated.
WordPress tracks and graphs pageviews only. However, they don't define pageviews. So you can only assume they are similar but not 'exactly' tracked like Google Analytics.
As well, there can be situations where JetPack conflicts with a WordPress update which can cause further complications with analytics. We like JetPack as it gives you a quick look at your stats, it's not intimidating and it does the job at the first glance. We use a minimum of three different analytic tools for BoardingArea—Google Analytics, JetPack, and Clicky. Because of the volume of traffic, we pay for all three tools and all three are available to the bloggers on the BoardingArea network to use. If you are trying to look at analytics for the purpose of revenue relationships, we highly suggest you focus solely on Google Analytics.
Now you know why Godzilla vs. Monster Zero ends the way it does.