When a child is childish, he gets scolded by adults and is expected to act properly.
When an adult is childish and a child noticed, the adults command them to understand and respect the adult who is acting like a teenager in his puberty.
When a child is wrong, the rule is to correct him right then and there.
When an adult is wrong, the rule is to shut up and just let it go.
When a kid knows better, he is asked to shut up and it is rarely that an adult encourages him to speak his mind.
When an adult knows better, he is a freaking genius and everyone should listen.
When a child did something wrong to someone, he is scolded.
When an adult did something wrong to a child, the adult will ask the child to understand the adult because he is an adult.
When a child is wrong, he is wrong.
When an adult is wrong, he is still right.
A child cannot be childish even if he is a child.
An adult can be childish without being reprimanded and he can still demand understanding from a kid.
SOMETHING MUST BE WRONG.
