• 17 Mar 2023

GA4 is almost here: 5 major differences between GA4 and UA, plus the pros and cons

Ready or not, Google Analytics 4 is coming. It’s been almost a year since Google dropped the bombshell that Universal Analytics would be deprecated from July 2023. Since then, many SEOs and site managers have been running both GA4 and UA — or “dual tagging” — in an effort to glean as much info as possible about GA4 before the switchover, without losing the functionality of UA.

Just like everyone else in SEO, we’ve been learning the fundamentals and discovering the possibilities of GA4 over the past year. In that time, we’ve started to pick up on some of the ways that the new property differs from Universal, and are now starting to see the bigger picture in terms of the new opportunities GA4 could offer — if you know how to unlock them.

Here, we’ll be sharing some of my key findings, along with a few of the biggest advantages and drawbacks we’ve found so far. Grab a coffee, and let’s get stuck in.

What are the key differences between GA4 and Universal?

First: exactly how does GA4 differ from its predecessor? We’ve outlined a few of the biggest differences below.

1.     Analytics Views are now data streams 

In GA4, you can track multiple “data streams” in a single Analytics property. So, if you have an app (iOS, Android, or both) and a website you can combine the tracking of these streams — unlike Universal, where you needed to have separate properties. You can then filter this data so you can have separate reports per stream, although you can also look at a combined view if preferred.

Data Streams can also come with built-in events if you select the “Enhanced Measurement” option when setting them up. Potential events include scrolls (scroll depth at the page level), file downloads, video plays, site search and outbound link clicks. In Universal Analytics, you would need to set these up manually as events.

2.     Everything is an Event

Universal Analytics offered different hit types for different interactions. For example, page views were a unique hit type; a transaction was a unique hit type, and so on. In GA4, everything is an event. The table below shows the difference quite well.

Events were already a thing in Universal, and they each had a category, action, and label. But this classification no longer exists in GA4.

Instead, events have event parameters (up to 25). Some of these are automatically collected like page_title, page_location, screen_resolution but you can also add custom ones. So, old events that were tracked in Universal can still be tracked in GA4 — it’s just that the classification system is different. 

3.     Session calculation is very different

The way Google calculates sessions for GA4 is different to Universal. In Universal, a session was a period of time that a user was actively engaged after landing on a page. A session would only end when there was either;

    • 30-minutes of inactivity (or whatever you set your session timeout at)
    • The clock passed midnight (this would create a new session)
    • New campaign UTM parameters were found

In GA4, the session_start event is triggered when a user lands on a page. This creates a unique session ID and every subsequent action taken on the website in that session is associated with that session ID. Of the three rules for sessions ending in Universal, only the session timeout clause applies to GA4.

4.     Bounce rate and user engagement is calculated differently

Google wants to become more positive when it comes to user engagement, and to this end have prioritised a new metric in reports called engagement rate.

This metric is calculated as engaged sessions / sessions. An engaged session is a session that lasted longer than 10 seconds, had at least one conversion event, or had at least two / screen views.

Bounce rate still exists in GA4, but it is calculated differently. It is now simply the percentage of sessions that were not engaged. In UA, the bounce rate was the number of users that didn’t view more than one page on your website. This means high bounce rates on pages such as contact pages should come down, as users interacting with phone numbers, emails, or other contact links would classify as being an engaged visit.

5.     Tag manager is super important

With UA you could get away with not using Tag Manager and instead implement more advanced features either directly in Analytics or through your website. In GA4 it is much easier (and in some cases essential) to use Tag Manager.  

Pros and cons of GA4 (so far)

Exactly how helpful — or annoying — each of the above changes will be depends on your setup and preferred tracking metrics. That said, there are a few potential pros and cons to the new Analytics.

Potential advantages

  • GA4 uses machine learning to help business owners predict the future. It does this via metrics deemed “Predictive metrics”. By collecting a myriad of events and session data, Google creates the following useful metrics:
    • Purchase probability:  The probability that a user who was active in the last 28 days will log a specific conversion event within the next 7 days.
    • Churn probability: The probability that a user who was active on your app or site within the last 7 days will not be active within the next 7 days.
    • Predicted revenue: The revenue expected from all purchase conversions within the next 28 days from a user who was active in the last 28 days.
  • Native event tracking and its automated use ensures you can spend more time analysing data on your customer journey rather than having to manually set up funnels, events etc.
  • The use of data streams is useful for businesses that have multiple traffic-driving assets (web, app, and so on) and gives both a holistic and separated view. When coupled with the above features, this can make GA4 a very powerful tool.


  • Historical data comparisons aren’t possible within the GA4 view, as the property tracks only from when it is set up. This can still be done manually; however, the changes to session definitions mean the data is not like for like, making the migration to GA4 more of a “fresh start”.
  • While this is one of those things that will improve with time, the switchover to GA4 will unavoidably create more work for professionals who rely on Analytics data. All the fundamentals are changing, and therefore teams — both in-house and agency-side — have to adapt to these changes to get the best out of the new data collection methods. Re-learning the basics will take time, and the process could disrupt workflow and so impact traffic and revenue.
  • Migrating from UA to GA4 can be complex, and sourcing expert knowledge is the only way to make sure it’s done correctly. Outside expertise won’t come for free — although it’s certainly much cheaper than a botched migration.

Hopefully, these tips and insights will have given you a few pointers on preparing for GA4. If you’ll be making changes to your Analytics tracking in the coming months, why not take the opportunity to start improving your site’s online visibility, too? Get in touch to learn more about what our SEO agency can do for your site today.

Marc Swann

Search Director

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