People forget that he's very like his mother in character. Diana wasn't in the least bit academically bright but she had emotional intelligence in bags and knew how to draw publicity to causes that needed it. I'm old enough to remember the compete panic and fear over AIDS in the 1980s when people who were HIV+ were completely shunned; she went into hospital and in full view of the cameras shook the hand of an AIDS patient without gloves, bare skin to bare skin. She also held HIV+ children in her arms in the USA. That was completely mind-blowing at the time. Just about the last thing she did in her life was bringing world attention to minefields left over from wars and their horrific effect; look at the impact that attention and consequent clearance has had to developing countries.
Harry was the son who set up Sentabale as a very young man, even before Invictus. Whenever you see him with children, even then, he's very like his mother, hands on, and cuddling and gently teasing them. When the Obamas were in the White House and he was doing flying training in the USA, he made time to unexpectedly appear at a White House event for military children and they loved it. Even if they were too young to know exactly who he was, the video shows that children react positively to him. Even at the time he was getting attention for drunken high jinks, he was doing this sort of thing which I don't think was publicised in the UK. You also saw this side of him in Australia and New Zealand. I really don't think that William has this sort of automatic rapport; while he will do things for the homeless etc, it doesn't seem to have this emotional core but more intellectual duty.