Hi,
I'd say the same application could not be configured in ADT7420, note that this is a digital sensor. Its outputs is just a digital word, proportional to the absolute temperature the sensor is exposed to. I'd say, if differential temperature is required, you could place a sensor in each of the location desired and by software calculate the temperature difference. However, the accuracy of each sensor will be the stated on the datasheet, depending on the temperature range.
Regards,
Lluis.