Question: if two people with more or less body build are standing on a corner, one feels hot and the other feels mild. what is causes feeling of heat ?

Different people: You have just shown a lovely example of how people differ -- and that these differences go deeper than physical makeup alone. We have different temperaments and preferences, different experiences of the same events. One feels "hot" and the other feels "mild". No right or wrong here -- just variability! or maybe the "hot" one is wearing secret silk underwear? That could make a difference. :-).