Help with automation- trigger if temp1 > temp2

I have two Xaiomi temperature sensors, one in the upper level of the house and one in the basement. In the summer it is not unusual for the basement to be 10-15° cooler than the rest of the house. I have added a blower into the ductworks that blows the cooler basement air into the upstairs registers. It drops the upstairs temperature by a few degrees making the air conditioner come on less frequent.

How can I write an automation that turns on the fan whenever xaiomi1 temperature is > xaiomi2 temperature?

See the example here: https://www.home-assistant.io/docs/automation/trigger/#numeric-state-trigger

automation:
  trigger:
    - platform: numeric_state
      entity_id: sensor.outside_temperature
      # Other entity ids can be specified for above and/or below thresholds
      above: sensor.inside_temperature

Thanks- I’ll try it tomorrow.