Marketers often try to choose between using GA4 or GTM, but it’s more useful to think about how to use them together. GA4 and GTM serve different purposes: GTM is responsible for deploying and managing tracking, while GA4 stores, analyzes, and reports data.
Let’s clarify what each platform does, go over the key differences between them, and help you decide when to use one, the other, or both in combination.
What is Google Analytics 4?
GA4 is Google’s analytics platform for websites and apps. It collects, processes, stores, and reports on website performance and user behavior (events, sessions, key events, purchases, etc.). You can use it to answer business-oriented questions like:
- “Which pages are driving sign-ups or purchases?”
- “How many people visited the website last week?”
- “Which user journeys most often precede a purchase or a lead?”
- “Which marketing channels convert best?”
Beyond standard reports, GA4 also lets you access advanced tools like Explorations (free-form reports), data-driven attribution, audience building and native integrations with other platforms, such as BigQuery, Google Tag Manager or Google Ads.
Tip: find out how to set up GA4 (whether you’re a new user or coming from Universal Analytics) in one of these articles: “Google Analytics 4 setup checklist for new adopters”; “Google Analytics 4 migration checklist”.
What is Google Tag Manager?
GTM is a tag management system. It lets you add, modify, and remove marketing and analytics tags through a web interface, without having to edit the source code each time. GTM itself does not store or report data – that’s reserved for GA4 – but it allows you to control what data to collect, when to send it (using triggers), how to enrich it (with variables), and which tools to send it to (GA4, Google Ads, LinkedIn, etc.)
Tip: learn more about GTM’s key concepts and step-by-step implementation in the article “How to set up Google Tag Manager on your website”.
8 key differences
What fundamentally sets GA4 and GTM apart, and why does it matter? Let’s take a closer look.
| Google Tag Manager | Google Analytics 4 | Why this matters | |
|---|---|---|---|
| Purpose | Tag management and deployment via a web interface. It decides what fires, when, and then forwards that data to destination tools. | Analytics platform that collects, processes, stores, and reports on user behavior for web and app data streams, using an event-based model. It turns incoming events into metrics, dimensions, and reports for analysis. | They’re complementary, not substitutes. |
| Data collection and reporting | Does not store or report data. It only transports data to tools like GA4, Google Ads, Meta, etc. | Stores and reports processed website/app data. Provides rich standard or tailored reports (Explorations), plus audiences and attribution views. | Expect zero reports in GTM. Do all your analysis in GA4. |
| Core configurations | Tags (what to send), triggers (when to send), variables (what parameters to include), consent settings, among others. | Events and parameters, key events (conversions), audiences, attribution settings, data retention, data filters, and links (Google Ads, BigQuery, Google Search Console, etc.). | Clear split of responsibilities and governance: implementation logic in GTM, measurement logic in GA4. |
| Integrations scope | Deploys many vendors from one place (GA4, Google Ads, Meta, LinkedIn, etc.). Supports custom templates and server-side GTM. | Integrates for analysis and activation (Google Ads conversions/audiences, BigQuery raw export, Looker Studio dashboards, etc.). | Think of GTM as a multi-tool deploy layer, and of GA4 as an analytics and activation hub. |
| Setup | Add the GTM container snippet to your website/app once. After that, changes are managed via GTM’s user interface (UI). | GA4 can be installed via GTM or directly with gtag.js. Choose one method to avoid duplicate hits (prefer GTM). | GTM provides speed, rollback, and fewer dev dependencies. Prefer installing GA4 via GTM to prevent double-counting and messy attribution. |
| Event concept | Events in GTM are conditions that trigger tags. They govern execution, not reporting. | Events in GA4 are data records (e.g., purchase, generate_lead) that GA4 processes and reports on, enriched with parameters. | Same word, different meaning. Mixing them up can lead to implementation errors. |
| Who uses it | Marketing ops, tech-savvy marketers, and developers, when needed. | Analysts, marketers, product teams, and leaders who define success metrics, analyze reports, build audiences, and make budget/product decisions. | Clarifies ownership and prevents accidental changes from everyone having access to everything. |
| QA and safety | Features like Tag Assistant (Preview/Debug), Workspaces, Versions/rollback, Environments (dev/stage/prod), and access controls. | Features such as DebugView (to view events in real time), key event validation, sampling indicators, change history, etc. | When testing, test twice: validate the firing logic in GTM, then validate event registration and parameters in GA4 before publishing. |
When to use one or the other?
If you want a 360º view and control over your website or app’s performance, there is only one correct answer: use both. GTM should be used to implement and manage tracking, while GA4 should serve as the data source and reporting layer. They’re complementary, not substitutes.
Of course, you can use one without the other, but there are only a few situations when this makes sense, namely:
-
GA4 without GTM
You might consider this approach for very small, rarely-changing websites that only have GA4 tracking and no other pixels. It can also be practical where strict IT/security policies prohibit using a tag manager. However, keep in mind that you will depend on developers for every update and miss out on GTM’s QA and versioning advantages.
-
GTM without GA4
This might only work if you’re sending events to other platforms, such as Google Ads or Meta, to a data warehouse or Customer Data Platform (CDP), and analyzing somewhere else. Note that GTM isn’t an analytics tool, so if you need behavioral reporting, you still need GA4 or another analytics destination.
Final thoughts
GA4 and GTM work best when used together. A winning formula where GTM manages how you collect data, and GA4 analyzes what that data means. By understanding what each tool does best and using them accordingly, you’ll complete your tracking and reports more quickly, easily, and at a lower cost.
For a deeper dive into using these tools together and what they can do for your business, read our “How Google Tag Manager fits into the GA4 setup” article. And if you’re looking at server-side options, have a read of “How to set up GA4 via GTM server-side tagging”.