Difference between calibrated and uncalibrated dat

[ezekielNVK22]

Hello, I would like to know the difference between the calibrated data obtained with the function and the uncalibrated data with the function . I would like to understand how this calibration is performed and which parameters are used for it. Are calibrated data more reliable than uncalibrated data?
Another question: Does the integration time regulate the sensitivity of the sensor? Would there be an ideal value to use?