Comparing Universal Analytics & GA4 for Link Campaigns

For years, Universal Analytics (UA) was the default analytics tool for marketers running link campaigns. It was predictable, familiar, and — like an old office chair — slightly uncomfortable but trusted. Then came Google Analytics 4 (GA4), and suddenly everyone had to relearn how sitting works.

If your campaigns rely on short URLs, redirects, UTMs, and cross-platform traffic, the differences between UA and GA4 are not academic. They directly affect what you see, what you trust, and what you optimise. This guide compares both systems specifically through the lens of link-based campaigns, not generic pageview tracking.

Why This Comparison Still Matters

If you are evaluating GA4 results against older UA benchmarks, define the exact decision you need to make. Is the goal budget allocation, channel performance, or a migration checklist? The answer changes which differences matter.

Universal Analytics is officially sunset, but its mental model still lives rent-free in many dashboards and spreadsheets. Teams migrating to GA4 often assume it is a “new interface for the same data.” It is not. GA4 represents a fundamentally different way of interpreting user behaviour — and that difference becomes painfully obvious once you start analysing short-link traffic.

If you have ever asked questions like: “Why does this campaign have fewer sessions than clicks?” or “Why does attribution suddenly look… creative?” then this article is for you.

The Core Tracking Model: Sessions vs Events

Universal Analytics: Session-Centric Thinking

UA was built around the idea of a session. A user arrives, a session starts, pages load, events fire, and eventually the session times out. Short links fit reasonably well into this model, especially when:

  • The redirect was fast.
  • UTMs survived intact.
  • The destination page loaded cleanly.

UA assumed continuity. Once a session started, most actions were interpreted as part of that same visit, even if the path to get there involved redirects.

GA4: Event-First Reality

GA4 flipped this model entirely. Everything is an event. Pageviews are events. Clicks are events. Sessions are reconstructed after the fact. This is powerful, but it also means GA4 is less forgiving when context is lost.

With short links, every redirect introduces a potential break in the event chain. If attribution data is missing or delayed, GA4 does not “fill in the blanks” the way UA often did. It simply records what it sees — and sometimes what it sees is incomplete.

UTM Handling: Familiar Names, Different Behaviour

Comparison diagram showing familiar metric names mapped to different event behaviors in GA4.

At first glance, UTMs look identical in both systems. Source, medium, campaign — same parameters, same syntax, same marketer optimism. The difference lies in when and how they are applied.

How UA Treated UTMs

UA attached UTMs at session start and largely trusted them. If a redirect chain resolved quickly, UA usually credited the session correctly. This made UA surprisingly tolerant of messy link setups.

It was not perfect, but it was predictable.

How GA4 Interprets UTMs

GA4 applies UTMs at the event level. If the first meaningful event fires without UTM context — even briefly — GA4 may attribute the session differently than expected.

This is why marketers migrating from UA often experience:

  • Sudden spikes in Direct traffic.
  • Campaign data appearing under unexpected sources.
  • Inconsistent attribution across platforms.

GA4 is not broken. It is simply honest in a way UA never was.

Redirect Chains: Tolerance vs Precision

Redirects are unavoidable in short-link ecosystems. Custom domains, HTTPS enforcement, device routing, geo logic — they all add hops.

UA’s High Tolerance

UA could tolerate multiple redirects as long as the final landing page loaded quickly. Even if the redirect chain took a scenic route, UA often credited the campaign correctly. It prioritised continuity over accuracy.

GA4’s Low Patience

GA4 is less forgiving. Every additional redirect increases the chance that:

  • UTM parameters are stripped.
  • Referrer data is lost.
  • The first event fires too late.

The result is not incorrect data — it is incomplete attribution. GA4 shows you exactly what survived the journey.

Attribution Models: Simpler vs Explicit

Universal Analytics Attribution

UA offered several attribution models, but most teams defaulted to last-click. It was simple, sometimes misleading, and widely understood.

Short links often benefited from this simplicity. If the click happened, it usually “counted.”

GA4 Attribution Reality

GA4 uses data-driven attribution by default. This sounds impressive — and it can be — but it requires clean, consistent signals. Short links with inconsistent UTMs or broken redirects confuse the model.

When GA4 lacks confidence, it does not guess. It falls back to safer defaults, which often means Direct.

Cross-Platform Traffic: UA’s Blind Spot vs GA4’s Strength

Diagram of web and app traffic converging into a single cross-platform analytics stream.

Here is where GA4 clearly wins. UA struggled with cross-device and cross-platform journeys. GA4 was built for them.

If your short links drive traffic from:

  • Mobile apps.
  • Social platforms.
  • QR codes.
  • Messaging tools.

GA4’s event-based model provides more flexibility — assuming the link infrastructure is solid. In other words, GA4 rewards discipline.

Decision Guide for Migration

  1. Audit your redirect chain length and remove non-essential hops.
  2. Lock down a single UTM naming convention across teams.
  3. Verify cross-domain measurement for any short-link to landing-page handoff.
  4. Run a 2-week parallel report to compare UA vs GA4 attribution deltas.

Which One Is Better for Link Campaigns?

The uncomfortable answer is: it depends on how mature your link setup is.

UA was forgiving. GA4 is precise. UA tolerated shortcuts. GA4 exposes them.

If your short-link system:

  • Minimises redirect hops.
  • Preserves UTMs end-to-end.
  • Loads destinations quickly.

Then GA4 will give you deeper, more reliable insights than UA ever could. If not, GA4 will still tell the truth — it just may not be the truth you hoped for.

Final Thoughts

Comparing Universal Analytics and GA4 is not about nostalgia versus novelty. It is about understanding that analytics does not create accuracy. Your infrastructure does.

GA4 did not make tracking harder. It made tracking more honest. And honesty, while occasionally uncomfortable, is the foundation of optimisation.

Or, put differently: UA let you believe your links were perfect. GA4 politely asks you to prove it.