Google Analytics Comparison: What’s Different in Google Analytics 4 (GA4)?

Google Analytics 4 is a new version of Google Analytics that builds on top of three technologies that include firebase analytics, among others. This post details the differences between traditional Google Analytics and Google Analytics 4 (GA4)

Since you’re reading this, you have likely spent quite a bit of time working with legacy versions of Google Analytics, and it’s also likely that you’re feeling intimidated by how different Google Analytics 4 (or GA4) appears to be. This post aims to introduce you to the new concepts that differentiate GA4 from its predecessors and give you confidence that it is a big step forward from what you are familiar with.

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Google Analytics Comparison

Google Analytics 4 is an entirely new version of Google Analytics that builds on top of three technologies that Google has been developing for the past few years:

    1. Firebase Analytics, which leverages the event-driven data model to better describe behavior, measure user engagement, and seamlessly roll up data across websites and mobile applications.
    2. Google Signals, which allows you to use Google’s identity software to recognize users who are not logged in.
    3. The global site tag, which allows you to enable features requiring code changes to a website without modifying tags

Each of the three items above represents a Google Analytics 4 difference and is designed to solve a problem with the legacy versions of Google Analytics, so let’s talk through each of them:

The Problem that Firebase Solves

If you’ve attempted to use the old Google Analytics mobile SDK or even install traditional Google Analytics on a single page web app, a piece of your heart already knows that these tools sometimes attempted to fit a round peg into a square hole. The fact is, apps are more variable than traditional websites, and the assumptions that we make about how users experience the web do not always hold true for how users experience a mobile app.

As an example, if you’re a runner, you might open a mobile app to track your speed and let it run in the background for hours. How many sessions should that create? Should every time you unlock your phone to check your pace be counted as a screen view?

Because it is built on top of Firebase Analytics, Google Analytics 4 simplifies the page view/screen view concept with a more flexible system of events and parameters. I refer to the new design as an event-driven data model.

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Yes, you can still use page views and screen views where it makes sense, but these are no longer the fundamental building blocks that they used to be. This is important because mobile apps are made up of a series of “activities” (things you can do) rather than “pages” (things you can see), and it can be unintuitive to try and use the concept of a screen view to describe the experience a user is having within your app.

These benefits may sound unclear at first, but once you start going down this rabbit hole, you’ll begin to notice ways that this approach actually works better on traditional websites as well. Think about the way we would track a purchase with traditional Google Analytics. The standard approach is to wait for a thank you page to load, set all of the transaction data as dimensions/metrics, and then fire a page view tag to pass all that data along (as demonstrated below).


But there are really two events happening in this scenario that are being crammed into one: the purchase event and the thank you page view event.

Also, the transaction data really only describes the purchase event, whereas the typical page information (page title, etc.) really only describes the page view event. Separating this into two events with their own parameters would be a more accurate representation of the actual activity occurring on your website.


The event-driven data model solves this problem by allowing you to create an event for any activity you would like to record and then attach the parameters to that event that are necessary to describe it.

Unlike Universal Analytics, GA4 can batch multiple events into a single hit. As a result, GA360 users do not necessarily need to worry about the cost of sending a high volume of events to GA4 properties, and there is no need to cram multiple actions into a single event. Building on the example above, if you happen to have a checkout flow without a thank you page, this is no problem; you just fire the “purchase” event.

As you will see, this event and parameter approach is an improvement for both traditional websites and mobile apps. And, bonus, since GA4 uses a common data schema on websites and mobile apps, you can roll up that data into nice dashboards for reporting purposes!

While we’re on the subject of cross-device reporting, let’s also discuss the next technology that Google Analytics 4 leverages: Google Signals.

The Problem that Google Signals Solves

I’ll keep this section short because I’ve already written a lengthy post about Google Signals and Privacy in Google Analytics 4, but the tl;dr is:

With the integration between Google Signals and Google Analytics 4, all of the reports in your GA4 property can leverage Google’s ability to identify users who visit your website or app multiple times from different devices (as long as they have enabled ad personalization)… even if they are not logged in.

This is a big deal because it means that you can get a very accurate picture of a small subset of users’ behavior on your site or application (those who are signed into Google and have opted-in to Ads Personalization). Google’s ML can then apply machine learning against this subset’s behavior to fill the data gaps that we know exist in the larger population, with a process they’re calling conversion modeling.

The legacy versions of Google Analytics did not handle the recent moves by browsers to restrict cookies. Using this solution, Google is able to embrace privacy without degrading the value of the work that we do as Analysts.
If you’re interested in learning more about this, take a look at my article above. Otherwise, let’s move on to gtag.

The Problem that gtag Solves

I was in the audience at the 2017 Partner Summit when Google announced the release of the global site tag, and many of us in the room that day were confused. After all, isn’t Google Tag Manager the recommended way to install Google marketing tags?

Three years later, with the release of Google Analytics 4, it’s starting to make sense. Here’s why:

The Analytics.js file that we used with early versions of Universal Analytics was a static file. It was identical for every website in the world that used Google Analytics. The global site tag, however, dynamically builds a javascript file for a measurement ID.

This means that Google can add features to the user interface that actually change the code that is installed on your site… like this:


That’s a big deal because it means that you can flip on cross-domain tracking or Enhanced Measurement features like video tracking in the interface, and automatically Google will deploy code to your site without the need for new tags.

This is why Google can claim that GA4 reduces the time that Analysts need to spend collecting data.

So those are the three big differences between traditional Google Analytics and Google Analytics 4, but I’m sensing that you have one final question:

Can I just use GA4 properties on my mobile apps and keep traditional GA on the web?

Google sort of forced us all to migrate our mobile apps to Firebase Analytics and GA4 from the old mobile app SDK back in October 2019, but you still have a choice on the web. By now, you can probably guess that I’m going to recommend that everyone add Google Analytics 4 to your website. Even if you do not have a mobile app, you should install GA4 on your website simply because: it’s free, it’s better, and you’re going to need to familiarize yourself with it because the industry is moving in that direction. However, you don’t have to pull the plug just yet. Keep your traditional Google Analytics tracking up and duplicate your data to a new GA4 property at first.

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