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Google Analytics 4 (GA4) offers several levels of traffic attribution to analyze more accurately where users come from and how they interact with your website or app. Among them are three metrics that may seem similar at first glance:
- First user default channel group
- Session default channel group
- Default channel group
As you can see, the difference is only in the first part of the name, which often causes questions and confusion among GA4 users. The same applies to other acquisition metrics like Source, Medium, Campaign, and others. We may see these names with prefixes like First user or Session.
Let’s clarify what the difference is and in what context each is used.
1. First user default channel group
What is it?
The channel through which the user first came to the website or app. Assigned at the user level and does not change even after subsequent visits.
Example:
If a user first arrived through Google Ads and then returned via Email or Direct, their first user default channel group will remain “Paid Search.”
Used in reports:
- Retention
- Lifetime Value
- Audiences and user-scoped conditions
2. Session default channel group
What is it?
The channel through which the user came during a specific session. Assigned at the session level and can change with each new visit.
Example:
If a user comes today via Email, the session default channel group = Email. Tomorrow they return via social networks – it will be “Organic Social.”
Used in reports:
- Standard traffic reports
- Conversion reports
- Funnels
- Segment comparisons
3. Default channel group
What is it?
This is the channel recorded at the event level. It shows through which channel the user came at the moment a specific event occurred.
Example:
User came via Paid Search, started a session, and at the 20th second clicked a button (event) – the default channel group for that event will be “Paid Search.”
Key features:
- Assigned at the event level, not user or session level
- Used in explorations and event reports
Comparison table
| Name | Level | What it shows | Changes over time? |
| First user default channel group | User | The first source the user came from | No |
| Session default channel group | Session | The traffic source of the current session | Yes |
| Default channel group | Event | The channel at the moment the event occurred | Yes |
The difference between First user default channel group and Session default channel group is easy to see working with the User acquisition and Traffic acquisition reports.
Difference between User acquisition and Traffic acquisition reports in GA4
GA4 has two key reports that analyze traffic sources but focus differently:
- User acquisition report shows where users came from the first time. In other words, this report attributes all user actions (including events and conversions) to the first channel through which the user accessed the site or app. This helps evaluate which channels bring new users.
- Traffic acquisition report focuses on each individual session. Here, each session is attributed to the traffic source from which it started, even if that source differs from the first one. This helps understand how users interact with the site or app in different sessions and which channels contribute to their engagement over time.
To analyze event-level acquisition metrics, you can create a report in explorations.
Example of the difference in counting user actions in different reports
Imagine this situation: A user first visits the site from Google Organic search. A few days later they return and start a session by clicking on Bing ads (bing / cpc). During this session, they browse several pages and then click a link in the company’s email newsletter (Email). At that moment, an important event happens – for example, the user adds a product to the cart (add_to_cart).
What will different reports show, and how will the event be attributed?
- In the User acquisition report, all user activity, including the add_to_cart event, will be attributed to Google Organic, since that was the user’s first source.
- In the Traffic acquisition report, the session will be attributed to Bing CPC because the session started from that source. The session’s source is Bing.
- But the add_to_cart event happened after the user clicked the Email link during the same session, so the event will be attributed to Email because events are always tied to the current traffic source, which can change within a session.
When to use what?
- Want to understand where new users come from? Look at First user default channel group.
- Analyzing behavior in a specific session? Use Session default channel group.
- Studying individual events or conversions? Pay attention to Default channel group.
