One user can own multiple devices. My friend owns an iPhone, an Apple Watch, and AirPods as well.
Also, the timeframes are different. Apple consider any device which pinged one of their services within the last 90 days to be active. So it's approximately 1 month vs 3 months in terms of the window of measurement. And we're not even getting into the possibility of devices pinging their services that aren't in true active usage, i.e. an iPad that's just charged and connected to WiFi but not actually used.
Of course, that's still extremely impressive from Apple! It's an amazing achievement which the market has obviously rewarded. But it's very much apples to oranges here. Those two statistics can't be directly compared because they represent different measurements over different periods of time.