The previous version of Google Analytics used a session-based tracking system that relied heavily on cookies. In contrast, GA4 uses event-based tracking and uses machine learning to decrease the dependency on cookies for data collection. In practice, this just means that more of the reports in GA4 are based on sampling and the reports are built on events (as opposed to sessions). If you are just starting with Google Analytics, this will not really affect you, but if you are switching from Universal Analytics, finding the reports you use on a regular basis may initially be a challenge.

GA4 is not a simple upgrade, it’s an entirely new piece of web application and the user interface is very different than the previous versions. For example, some of the default reports you may be using in Universal Analytics no longer exist. If you are used to clicking on a report dimension and getting more detailed information, this user flow is also not available. Instead, dimensions and metrics are selected through the drop down menus on the column headers in the report tables.

The new measurement and reporting approach provides a more detailed understanding of user behavior and enables businesses to track specific actions such as button clicks, video views, or form submissions. Some of the events that had to be manually configured, such as file downloads and scrolls are now in the default reports.

In addition, GA4 includes enhanced machine learning capabilities, which are designed to provide more accurate insights and predictions. The platform leverages Google's advanced AI technology to identify trends, segment audiences, and generate valuable insights automatically. These features are likely to evolve over time and ensure data availability even if more and more websites are limiting the use of cookies for tracking. GA4 is designed to adapt to a future with or without cookies or identifiers. As third-party cookies are phased out, GA4 can use machine learning to help fill the gaps where data is incomplete.