Question

why is there hardly any difference in day and night temperature in andaman and nicobar island and Kerala is 7 or 8 whereas in that desert it is between 25 to 30

Answer 1

Because it lay between the equator of the earth
hope this will help you

Answer 2

The answer is
Kerala and andaman nicobar island are very near to the equator. And equator is 0°c where also there is any diff. between day and night