Simple answer is that on your iPhone your Wifi OR Bluetooth NEED to be on (doesn’t have to be both) and on the other device the Wifi or Bluetooth also needs to be on (again, not both). Put another way: your iPhone is being used as a communication device (either via Wifi or BT), so it needs to be ‘On’… likewise, the device you want to be able to connect TO the iPhone needs to be ON in order to connect (via Wifi or BT). Apple is probably a little more stringent on security that Android…