UA vs. GA4

This Google doc is really helpful in figuring out how Google Analytics are defined differently in GA4. There are several differences, but here are some of the most important.

Users: UA counted all users, GA4 focuses on unique active users. This will cause GA4 users to appear lower. Other factors like filters in UA may further cause the data to be different.

Pageviews/Views:Google says these metrics should be very similar between UA and GA4. Differences may be caused by UA filters and app data.

Purchases: “Web purchase counts should match closely. We never expect all events to be collected perfectly, and purchase events are no exception to that rule, however these events are atomic and critical so event counts should match closely across UA/GA4… If you are comparing recent reports, you might see differences because GA4 is still processing data.”

Sessions: UA restarts session count at midnight, GA4 does not. ” Google Analytics 4 properties use a statistical estimate of the number of sessions that occurred on your website or app by estimating the number of unique session IDs, while Universal Analytics properties don’t estimate the number of sessions. The estimates used by Google Analytics 4 properties more efficiently count sessions with high accuracy and low error rate.”

Conversions: Destination (thank-you page tracking) should be “quite close”.  GA4 usually counts every instance of the conversion event, even if the same conversion event is recorded multiple times during the same session. So, if a user submits the form twice during the same session, two conversions will be counted, but you can change this in the counting method settings. GA4 can also take longer to process data.