GA4 vs UA: what actually changed (and why it matters)

If you used Universal Analytics for years and jumped into GA4, you probably felt lost. The interface looks different, the metrics have new names, and some familiar features are just... gone.

I've been through this transition myself and helped countless clients make the switch. Let me break down the real differences between UA and , not just the surface-level stuff, but the conceptual changes that actually matter.

The core difference: data models

Everything else flows from this fundamental change.

Universal Analytics used a session-based model. Data was organized around , a period of user activity on your site. Within sessions, you had "hits" (pageviews, events, transactions).

GA4 uses an event-based model. Every interaction is an event. Pageviews are events. Clicks are events. Scrolls are events. There's no separate concept of "hits" anymore.

Universal Analytics (Session-Based)
────────────────────────────────────
Session
  └── Pageview (hit)
  └── Event (hit)
  └── Transaction (hit)
  └── Social (hit)

GA4 (Event-Based)
────────────────────────────────────
User
  └── page_view (event)
  └── click (event)
  └── purchase (event)
  └── [any custom event]

This might seem like semantics, but it changes how you think about tracking. In UA, you'd set up goals and funnels. In GA4, you mark certain events as "key events" and build explorations.

Side-by-side comparison

Metrics that changed

This is where most of the confusion happens. Same concepts, different , or completely new approaches.

Users

Important: When GA4 reports show "Users," they mean Active Users by default. This is different from UA's "Users" which counted everyone.

Sessions and engagement

GA4's engagement rate is basically the inverse of bounce rate, but with a clearer definition:

Engaged Session =
  Session > 10 seconds
  OR session has a key event
  OR session has 2+ page views

Engagement Rate = Engaged Sessions ÷ Total Sessions

Goals and conversions

In March 2024, GA4 renamed "Conversions" to "Key Events." The term "Conversions" now only applies when data is sent to Google Ads. Confusing, but important to know.

Reports comparison

The reporting interface is completely different. Here's how to find what you're used to:

Standard reports

Custom analysis

GA4's Explorations are actually more flexible than UA's custom reports, but they have a learning curve. For simpler visualizations, many people prefer Looker Studio or tools like Analayer.

Features you lost

Let's be honest about what's gone:

Views are gone

In UA, you could create multiple views of the same data with different filters. Want to see just mobile traffic? Create a view. Just US traffic? Another view.

GA4 doesn't have views. Instead, you use:

• Data filters (for permanent filtering like internal traffic)
• Comparisons (for temporary segmentation in reports)
• Segments (for analysis in Explorations)
• Separate properties (for truly separate data)

Some reports disappeared

• Content Drilldown → Use Pages and screens report with path exploration
• Site Speed → Replaced by Core Web Vitals (via Search Console integration)
• Reverse Goal Path → Use Path exploration in reverse
• Goal Flow → Use Funnel exploration

Historical data comparison

You can't compare UA and GA4 data directly. The data models are too different. A "session" in UA isn't the same as a "session" in GA4. Set a new baseline in GA4 and measure forward from there.

Features you gained

It's not all losses. GA4 brought some genuine improvements:

Free BigQuery export

This was a GA360-only feature. Now everyone gets access to raw, unsampled data in BigQuery. If you're doing serious analysis, this is huge. Learn more about connecting GA4 to BigQuery.

Better cross-platform tracking

One GA4 property can track your website AND your iOS app AND your Android app. User journeys across platforms become visible. This was technically possible in UA but required a lot of setup.

Built-in predictive metrics

With enough data, GA4 can predict:

• Purchase probability
• Churn probability
• Predicted revenue

These aren't gimmicks. They're genuinely useful for building audiences.

Improved privacy defaults

• IP anonymization is always on
• Better Consent Mode integration
• Shorter default data retention (controversial, but privacy-forward)

More custom dimensions

UA gave you 20 custom dimensions and 20 custom metrics. GA4 gives you 50 of each. That's a meaningful upgrade for complex tracking needs.

The learning curve

Here's the honest truth: GA4 has a steeper learning curve than UA. The interface is less intuitive, the concepts are different, and you need to unlearn some habits.

But once you get it, GA4's event-based model is actually more flexible. You can track complex user journeys more easily. The analysis tools (Explorations) are more powerful.

My recommendation:

1. Spend time in Explorations. That's where the power is
2. Accept that you need to build new muscle memory
3. Use tools that simplify the interface if you're not an analyst

Practical migration tips

If you're still getting comfortable with GA4:

1. Stop looking for 1:1 equivalents: Some things don't translate directly. Accept it.
2. Focus on key events first: Get your conversions set up before optimizing everything else.
3. Use DebugView religiously: It's your best friend for verifying events.
4. Set up BigQuery now: Even if you don't use it yet, future you will be grateful.
5. Give it time: The GA4 interface improves regularly. It's much better than launch.

For a step-by-step setup guide, check our GA4 initial setup checklist.

The bottom line

GA4 is different, not worse. The event-based model is more flexible. The privacy features are better. Cross-platform tracking finally works properly.

The transition is painful, but the platform is solid. Give yourself time to learn it.

And if you want a simpler way to access your GA4 data, try Analayer for free. We built it specifically for people who need actionable insights without the complexity of the native interface.