Lets take a look at this based on the facts. We use a thermocouple to measure the extruder head temp which creates a voltage in microvolts that is amplified and then sent to the microcontroller on the EC. At the same time, we use a thermistor (a variable resistor that changes value based on temp) but is known to be non-linear and also has a fair amount of variation out of the box.
To put it finely—yes, it's pretty much a given the two devices will not report the same temperature without some serious calibration. In fact, due to the completely different nature of the two devices, it's highly likely even after basic calibration they would never show the same temperature from cold to hot. The truth is, that's perfectly fine. We could care less what the actual temp really is (within some reason). What matters is that the device is precise (gets the same measurement each time). Accuracy is the measured value VS a known calibrated value. We tune our machines with the test cubes to come to the right temp your machines extrudes at. If that's 207C like mine-fine, or if yours needs 230C, no big deal.
Also, I'm not sure how you measured temp but my non-contact infrared thermometer from Harbor freight must be set to record MAX temp while I find the sweet spot. I know for a fact the nozzle will never report the same temp at the heat block due to thermal resistance and heat loss. Again, we don't care one bit. What matters is the temp that prints best for you with the calibration blocks I find the bridge test one is best because too hot and the plastic bridging the gap will sag. Too cold and the extruder is known to jam.
For the record, I have also tried a contact digital thermometer which also showed much lower temps than reported in the control panel. The bottom line is that you are likely the exact same temps as the rest of us and we just never even knew what the actual temp was. Also, never really put much weight on the fact the two devices read the same temp at room temp. Due to the non-linear nature of the thermistor, this would be proof that at proper operating temps you are way off the actual value. The calibration in the EC preferences doesn't fix non-linearity. That being the case, I would rather they were way off at room temp and dead correct at operating temp.
