From Jeffrey Mincey on HomePod Siri vs Mac Siri:
Siri is different on each device. What you ask on HomePod won’t get the same response as the same query on iPhone. That’s just wrong. By necessity, Siri’s actions and tasks differ from one device to another. Queries should not. Siri has a severe personality disorder.
Siri on iPhone is best. Why the differences, Apple?