Oh it's not a one shot comparison, it's a continuous comparison, day by day.
The apogee is ventilated but you can decide the power on the ventilation and you can also decide the speed of ventilation.
I use the apogee like reference.
With solar radiation major then 400w/mq and wind near 0 km/h you begin to see the differfence between the screens.
Thanks to the specific construction of the meteohelix usually is only 1 degree more the full working ventilated apogee, the Davis and the netatmo (in the SIAP screen) usually is more then 2 degrees then the apogee.
Some other graph in the past is here:
http://www.kwos.org/weather/weewx/Compare/