"Warm" moderate temperature. "Hot" high temperature. A day that is 25C is warm. A day that is 35C is hot.

I think hot expresses higher comparative degree than warm , Warm is moderately hot . I think when it comes to be an adjective that doesn't denote temperature : Hot is something like "sexy" , but Warm is something like "passionate "

"Warm" also expresses a feeling of comfort. If the coffee is warm, it's temperature is high but not high enough to cause pain. You could also describe a person as warm which would mean they are caring/compassionate. "Hot" represents a temperature that is really high and that usually causes discomfort. If the coffee is hot, you wouldn't want to drink it right away because it may burn your mouth! lol As said previously, hot could be used to describe someone who is very attractive/sexy as well.