Mobile Hot Spot or Bluetooth tethering, which uses less battery

[EndRacism]

I want to routinely use one phone to run off a primary phone connections.

With Mobile Hot Spot or Bluetooth tethering, which uses less battery?

 

[Rukbat]

If you're using WiFi hotspot, it uses the same power as Bluetooth - they're both 2.4GHz radio (the same radio, in fact). If you're using wired hotspot (through the phone's USB connector), that uses a little less power.