Dan Petrov (via SixColors):

It seems that Apple has quietly added a new tool in macOS Monterey for measuring your device’s Internet connectivity quality. You can simply call the executable networkQuality, which executes the following tests:

• Upload/download capacity (your Tx/Rx bandwidth essentially)
• Upload/download flows, this seems to be the number of test packets used for the responsiveness tests
• Upload/download responsiveness measured in Roundtrips Per Minute (RPM), which according to Apple, is the number of sequential round-trips, or transactions, a network can do in one minute under normal working conditions

The advantages of networkQuality tool:

While these tools measure a few more metrics like latency to a target server, they both only measure capacity, and do this only in serial mode (the download and upload speed tests are done sequentially one after the other).

On the other hand, networkQuality measures the upload/download capacity and responsiveness in parallel by default

To test this yourself, fire up Terminal (it’s in Applications > Utilities) and type networkQuality (don’t sweat the cap Q in the middle, either will work). I’ve found that there are significant differences between the upload/download speeds reported by networkQuality and web-based tools like speedtest.net.

According to Apple’s official tech note:

The Apple Network Responsiveness test reports its results using a measure called Round-trips Per Minute (RPM). The RPM is the number of sequential round-trips, or transactions, a network can do in one minute under normal working conditions.

Guessing the differences are the measurement metrics, as well as a different destination server for each. Please do ping me with any insights.