Personal Hotspot Use linked to an iPad or MacBook
John & Dave,
Do you know if a person consumes more data connecting to an external device (iPad or MacBook) vs on then using iPhone alone?
It's possible, yes. Your iPad can be set to not use mobile/cellular data for specific apps, whereas it will always use Wi-Fi, regardless of the origin of that Wi-Fi signal. Similarly, app updates over 150MB won't happen over cell data, but will happily go over Wi-Fi.
So yes, depending upon what you're doing, you can easily use more data on Wi-Fi than on cell without knowing it.
On the Mac using something like TripMode would be potentially helpful for reducing bandwidth usage.