You can expect differences in user counts between Google Analytics 4 properties and Universal Analytics Standard/360 properties under the following circumstances:
- The two types of properties are using different user-identity methods, for example, the Google Analytics 4 property is using User-ID and the Standard/360 property is using Client ID.
- Google Analytics 4 properties focus on active users (users who are currently engaged), while Standard/360 properties focus on total users.
- Google Analytics 4 property report data by default includes all data streams, while in Standard/360 you have to add specific data streams via filters in report settings.
- Google Analytics 4 properties currently do not support filters, while data in Standard/360 reporting may be subject to view filters that exclude data.
- The method by which Analytics counts users can have a different margin of error for Google Analytics 4 properties than for Universal Analytics Standard/360 properties.