I was looking at Notebookcheck's tests of laptop and smartphone speed. They used iperf, showing (for instance) that the iPhone X could receive at over 900 Mbps. This, curiously, is much higher than even gaming laptops or workstations seem to get on their site, generally around 600 Mbps.
Now, using Ookla speedtest on a gigabit connection and an 802.11 ac router with 160 MHz capabilites, I've never been able to get close to their iPhone speeds. Further, I can get over 900 Mbps on one of the laptops they reviewed as getting only about 600 Mbps on iperf.
What's the difference between what iperf and Ookla are measuring that's causing this discrepancy?