Is there such a big difference between 36℃ and 38℃

Yes There is such a big difference between 36℃ and 38℃. 36℃ is slightly lower than body temperature, and 38℃ is higher than body temperature. Just from the point of view of human body temperature, of course, 38℃ is hotter and 36℃ is cooler. Summer is not only a matter of weather temperature, but also a matter of humidity.