If you have a sensor with temperature as the state and humidity as an attribute, then an update with the same temperature but a different humidity will update last_updated but not last_changed, as only the attribute has been updated.
The four possibilities for an update:
- Temperature changed, humidity changed → both times changed (state change)
-
Temperature static, humidity changed → only
last_updatedchanged (attribute change only) - Temperature changed, humidity static → both times changed (state change)
- Both static → neither time changed