You need to trust both.

The thermostat setup does not mean it is the temp that will be read in the enclosure, sometimes it is however most of the time the t-stat will be set a little higher than what the temperature you will read in your enclosure. You have to take in consideration the distance of the between UTH and enclosure, thickness of the enclosure etc

So it is normal to have different reading between both, your goal is to play around and see what setting on your T-stat allows you to provide the proper temp in your enclosure.

And as mentioned temps on UTH will not be uniform but should remain within a few degrees.