I reviewed a few Shopify clients and compared two metrics: Shopify's Visitors vs. GA4's Total Users. Based on 13 accounts that I looked at (see table below), GA4 reports 20% fewer Total Users on average than Shopify's Visitors. 

The number of sessions between platforms matches up well (GA4, on average, reports 97% of Shopify's Sessions). The discrepancy between the two user metrics has to do with Google's ability to "merge" two different users (read 'devices/browser' entities) into one based on extra "reporting identities" such as User ID (where present) and Google Signals. 

A user logged into their Google account that browses the www.slicedbread.agency site from two different devices will be counted as one Total User. Shopify will count it as two Visitors. 

Who doesn’t  have a Google account these days, anyway? 

Why did I look at Google's "Total Users" instead of the "Users" metric?

One of Shopify's metrics is called "Visitors." A similar metric in Google Analytics 4 is "Total Users." When you open GA4 reports, you will most often see a metric called "Users," but it tells you the number of users who were "engaged" (a subset), not the total number of all users. 

An engaged user has at least one "Engaged Session" (lasted longer than 10 seconds, had a conversion event, or had two or more screen or page views.) in the date range selected. 

As such, the number of "Users" will always be fewer than the number of "Total Users." 

The "Total Users" metric is also available, but it is hidden:

You would either need to edit a standard report to add it to the table or use the Explorations (custom reports). That being said, the difference between Users and Total Users metrics is not that significant most of the time:

Still, if we were to compare the two platforms, the total users would be "closer" to Shopify's visitors. 

Shopify reports all users, not only those who were engaged. As such, if we compare two metrics between the platforms (and that's what this email is about), it would have to be Shopify's Visitors vs. GA4's Total Users.

Next time a client asks you why the Visitors metric in Shopify is higher than GA's Users or Total Users, you will know. 

Hey, look at you, you just became a bit smarter!